Not printing to laserjet 4050 from Ubuntu 12.04

I am unable to print from Ubuntu 12.04 to HP LaserJet 4050 Printer. The Data is certainly sent to the Printer as this is acknowledged by a flashing light, and then nothing happens. The Printer Driver could not be installed by HPToolBox.
Occasionally, disconnecting the USB cable and then reinserting sometimes helps (though this tends to be a sporadic solution)

The output from: hpcheck -t is:

drjoe@onesimus:~$ hp-check -t

HP Linux Imaging and Printing System (ver. 3.12.2)
Dependency/Version Check Utility ver. 14.3

Copyright (c) 2011-14 Hewlett-Packard Development Company, LP
This software comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to distribute it
under certain conditions. See COPYING file for more details.

Note: hp-check can be run in three modes:
1. Compile-time check mode (-c or --compile): Use this mode before compiling the
HPLIP supplied tarball (.tar.gz or .run) to determine if the proper dependencies
are installed to successfully compile HPLIP.
2. Run-time check mode (-r or --run): Use this mode to determine if a distro
supplied package (.deb, .rpm, etc) or an already built HPLIP supplied tarball
has the proper dependencies installed to successfully run.
3. Both compile- and run-time check mode (-b or --both) (Default): This mode
will check both of the above cases (both compile- and run-time dependencies).

Saving output in log file: hp-check.log

Initializing. Please wait...

---------------
| SYSTEM INFO |
---------------

Basic system information:
Linux onesimus 3.2.0-24-generic-pae #37-Ubuntu SMP Wed Apr 25 10:47:59 UTC 2012 i686 i686 i386 GNU/Linux

Distribution:
ubuntu 12.04

Checking Python version...
OK, version 2.7.3 installed

Checking PyQt 4.x version...
OK, version 4.9.1 installed.

Checking for CUPS...
Status: scheduler is running
warning: Version: (cups-config) Not available. Unable to determine installed version of CUPS.)
error_log is set to level: warn

Checking for dbus/python-dbus...
dbus daemon is running.
python-dbus version: 1.0.0

------------------------------------
| COMPILE AND RUNTIME DEPENDENCIES |
------------------------------------

note: To check for compile-time only dependencies, re-run hp-check with the -c parameter (ie, hp-check -c).
note: To check for run-time only dependencies, re-run hp-check with the -r parameter (ie, hp-check -r).

Checking for dependency: CUPS - Common Unix Printing System...
OK, found.

Checking for dependency: CUPS DDK - CUPS driver development kit...
warning: NOT FOUND! This is an OPTIONAL/RUNTIME ONLY dependency. Some HPLIP functionality may not function properly.

Checking for dependency: CUPS devel- Common Unix Printing System development files...
error: NOT FOUND! This is a REQUIRED/COMPILE TIME ONLY dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: CUPS image - CUPS image development files...
error: NOT FOUND! This is a REQUIRED/COMPILE TIME ONLY dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: DBus - Message bus system...
error: NOT FOUND! This is a REQUIRED dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: gcc - GNU Project C and C++ Compiler...
error: NOT FOUND! This is a REQUIRED/COMPILE TIME ONLY dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: GhostScript - PostScript and PDF language interpreter and previewer...
OK, found.

Checking for dependency: libcrypto - OpenSSL cryptographic library...
error: NOT FOUND! This is a REQUIRED dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: libjpeg - JPEG library...
error: NOT FOUND! This is a REQUIRED dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: libnetsnmp-devel - SNMP networking library development files...
error: NOT FOUND! This is a REQUIRED dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: libpthread - POSIX threads library...
OK, found.

Checking for dependency: libtool - Library building support services...
error: NOT FOUND! This is a REQUIRED/COMPILE TIME ONLY dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: libusb - USB library...
error: NOT FOUND! This is a REQUIRED dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: make - GNU make utility to maintain groups of programs...
OK, found.

Checking for dependency: PIL - Python Imaging Library (required for commandline scanning with hp-scan)...
OK, found.

Checking for dependency: PolicyKit - Administrative policy framework...
OK, found.

Checking for dependency: PyQt 4 DBus - DBus Support for PyQt4...
OK, found.

Checking for dependency: Python DBus - Python bindings for DBus...
OK, found.

Checking for dependency: Python devel - Python development files...
error: NOT FOUND! This is a REQUIRED/COMPILE TIME ONLY dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: Python libnotify - Python bindings for the libnotify Desktop notifications...
OK, found.

Checking for dependency: Python XML libraries...
OK, found.

Checking for dependency: Python 2.3 or greater - Required for fax functionality...
OK, found.

Checking for dependency: Python 2.2 or greater - Python programming language...
OK, found.

Checking for dependency: Reportlab - PDF library for Python...
OK, found.

Checking for dependency: SANE - Scanning library...
OK, found.

Checking for dependency: SANE - Scanning library development files...
error: NOT FOUND! This is a REQUIRED/COMPILE TIME ONLY dependency. Please make sure that this dependency is installed before installing or running HPLIP.

Checking for dependency: scanimage - Shell scanning program...
OK, found.

Checking for dependency: xsane - Graphical scanner frontend for SANE...
warning: NOT FOUND! This is an OPTIONAL/RUNTIME ONLY dependency. Some HPLIP functionality may not function properly.

----------------------
| HPLIP INSTALLATION |
----------------------

Currently installed HPLIP version...
HPLIP 3.12.2 currently installed in '/usr/share/hplip'.

Current contents of '/etc/hp/hplip.conf' file:
# hplip.conf. Generated from hplip.conf.in by configure.

[hplip]
version=3.12.2

[dirs]
home=/usr/share/hplip
run=/var/run
ppd=/usr/share/ppd/hplip/HP
ppdbase=/usr/share/ppd/hplip
doc=/usr/share/doc/hplip-doc/HTML
icon=no
cupsbackend=/usr/lib/cups/backend
cupsfilter=/usr/lib/cups/filter
drv=/usr/share/cups/drv

# Following values are determined at configure time and cannot be changed.
[configure]
network-build=yes
pp-build=yes
gui-build=yes
scanner-build=yes
fax-build=yes
dbus-build=yes
cups11-build=no
doc-build=yes
shadow-build=no
hpijs-install=yes
foomatic-drv-install=yes
foomatic-ppd-install=yes
foomatic-rip-hplip-install=no
hpcups-install=yes
cups-drv-install=yes
cups-ppd-install=no
internal-tag=3.12.2
restricted-build=no
ui-toolkit=qt4
qt3=no
qt4=yes
policy-kit=yes
hpijs-only-build=no
lite-build=no
udev-acl-rules=yes
hpcups-only-build=no
hpijs-only-build=no

Current contents of '/var/lib/hp/hplip.state' file:
# hplip.state - HPLIP runtime persistent variables.

[plugin]
installed=0
eula=0

Current contents of '~/.hplip/hplip.conf' file:
[settings]
systray_visible = 0
systray_messages = 0

[last_used]
device_uri = "hp:/net/Photosmart_C4380_series?zc=HPF2FD23"
printer_name =
working_dir = .

[commands]
scan = /usr/bin/simple-scan %SANE_URI%

[refresh]
rate = 30
enable = false
type = 1

[polling]
enable = false
interval = 5
device_list =

[fax]
voice_phone =
email_address =

[installation]
date_time = 05/05/12 14:27:05
version = 3.12.2

--------------------------
| DISCOVERED USB DEVICES |
--------------------------

No devices found.

---------------------------------
| INSTALLED CUPS PRINTER QUEUES |
---------------------------------

Hewlett-Packard-HP-LaserJet-4050-Series
---------------------------------------
Type: Unknown
Device URI: usb://HP/LaserJet%204050%20Series
PPD: /etc/cups/ppd/Hewlett-Packard-HP-LaserJet-4050-Series.ppd
PPD Description: HP LaserJet 4050 Series Postscript (recommended)
Printer status: printer Hewlett-Packard-HP-LaserJet-4050-Series is idle. enabled since Sending data to printer. BST
warning: Printer is not HPLIP installed. Printers must use the hp: or hpfax: CUPS backend to function in HPLIP.

Photosmart_C4380
----------------
Type: Printer
Device URI: hp:/net/Photosmart_C4380_series?zc=HPF2FD23
PPD: /etc/cups/ppd/Photosmart_C4380.ppd
PPD Description: HP Photosmart c4380 Series, hpcups 3.12.2
Printer status: printer Photosmart_C4380 is idle. enabled since Fri 04 May 2012 15:47:27 BST
Communication status: Good

----------------------
| SANE CONFIGURATION |
----------------------

'hpaio' in '/etc/sane.d/dll.conf'...
'hpaio' in '/etc/sane.d/dll.d/hplip'...
OK, found. SANE backend 'hpaio' is properly set up.

Checking output of 'scanimage -L'...
device `hpaio:/net/Photosmart_C4380_series?zc=HPF2FD23' is a Hewlett-Packard Photosmart_C4380_series all-in-one

---------------------
| PYTHON EXTENSIONS |
---------------------

Checking 'cupsext' CUPS extension...
OK, found.

Checking 'pcardext' Photocard extension...
OK, found.

Checking 'hpmudext' I/O extension...
OK, found.

Checking 'scanext' SANE scanning extension...
OK, found.

---------------
| USER GROUPS |
---------------

drjoe adm cdrom sudo dip plugdev lpadmin sambashare vboxusers

error: User needs to be member of group 'lp' to enable print, scan & fax.
User member of group 'lpadmin'.

-----------
| SUMMARY |
-----------

error: 14 errors and/or warnings.

Please refer to the installation instructions at:
http://hplip.sourceforge.net/install/index.html

Done.