Problems using scanner Benq 5000 /E/U with Ubuntu 10.10

I have a scanner Benq 5000 E/U but simple scan dumps when I try to use it .. I add the information required
 except for the error I can't understand why command "sane-find-scanner" indicates a FlatbedScanner 22 meanwhile command "scanimage -L" indicates a FFlatbedScanner25.. Maybe this is the problem. Another problem I have is that I have to start the "simple-scan" program as root, but this bother less.
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incensus@Incensus-Ubuntu:~$ cat /etc/issue
Ubuntu 10.10 \n \l
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incensus@Incensus-Ubuntu:~$ sudo simple-scan -d
[sudo] password for incensus:
** (simple-scan:2050): DEBUG: Starting Simple Scan 2.32.0, PID=2050
** (simple-scan:2050): DEBUG: Restoring window to 520x400 pixels
** (simple-scan:2050): DEBUG: sane_init () -> SANE_STATUS_GOOD
** (simple-scan:2050): DEBUG: SANE version 1.0.21
** (simple-scan:2050): DEBUG: Requesting redetection of scan devices
** (simple-scan:2050): DEBUG: Processing request
** (simple-scan:2050): DEBUG: sane_get_devices () -> SANE_STATUS_GOOD
** (simple-scan:2050): DEBUG: Device: name="snapscan:libusb:002:002" vendor="Acer" model="FlatbedScanner25" type="flatbed scanner"
** (simple-scan:2050): DEBUG: Requesting scan at 300 dpi from device 'snapscan:libusb:002:002'
** (simple-scan:2050): DEBUG: scanner_scan ("snapscan:libusb:002:002", 300, SCAN_SINGLE)
** (simple-scan:2050): DEBUG: Processing request
** (simple-scan:2050): DEBUG: sane_open ("snapscan:libusb:002:002") -> SANE_STATUS_IO_ERROR

** (simple-scan:2050): WARNING **: Unable to get open device: Error during device I/O
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incensus@Incensus-Ubuntu:~$ sane-find-scanner

  # sane-find-scanner will now attempt to detect your scanner. If the
  # result is different from what you expected, first make sure your
  # scanner is powered up and properly connected to your computer.

  # No SCSI scanners found. If you expected something different, make sure that
  # you have loaded a kernel SCSI driver for your SCSI adapter.

found USB scanner (vendor=0x04a5 [Color], product=0x20fc [ FlatbedScanner 22]) at libusb:002:002
  # Your USB scanner was (probably) detected. It may or may not be supported by
  # SANE. Try scanimage -L and read the backend's manpage.

  # Not checking for parallel port scanners.

  # Most Scanners connected to the parallel port or other proprietary ports
  # can't be detected by this program.

  # You may want to run this program as root to find all devices. Once you
  # found the scanner devices, be sure to adjust access permissions as
  # necessary.
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incensus@Incensus-Ubuntu:~$ scanimage -L
device `snapscan:libusb:002:002' is a Acer FlatbedScanner25 flatbed scanner
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incensus@Incensus-Ubuntu:~$ lsusb
Bus 002 Device 002: ID 04a5:20fc Acer Peripherals Inc. (now BenQ Corp.) Benq 5000
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 003: ID 0bda:0158 Realtek Semiconductor Corp. USB 2.0 multicard reader
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
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incensus@Incensus-Ubuntu:~$ ls -l /dev/bus/usb/*/*
crw-rw-r-- 1 root root 189, 0 2011-01-12 13:06 /dev/bus/usb/001/001
crw-rw-r-- 1 root root 189, 2 2011-01-12 13:06 /dev/bus/usb/001/003
crw-rw-r-- 1 root root 189, 128 2011-01-12 13:06 /dev/bus/usb/002/001
crw-rw-r--+ 1 root root 189, 129 2011-01-12 13:08 /dev/bus/usb/002/002
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incensus@Incensus-Ubuntu:~$ dmesg | grep usb
[ 0.260670] usbcore: registered new interface driver usbfs
[ 0.260680] usbcore: registered new interface driver hub
[ 0.260701] usbcore: registered new device driver usb
[ 0.847906] usb 1-7: new high speed USB device using ehci_hcd and address 3
[ 1.537868] scsi10 : usb-storage 1-7:1.0
[ 1.537930] usbcore: registered new interface driver usb-storage
[ 1.840008] usb 2-1: new full speed USB device using ohci_hcd and address 2
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incensus@Incensus-Ubuntu:~$ ls -l /usr/share/sane/snapscan/
totale 64
-rw------- 1 root root 65280 2001-07-16 02:38 U252V065.BIN
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incensus@Incensus-Ubuntu:~$ sudo gedit /etc/sane.d/snapscan.conf

#------------------------------ General -----------------------------------

# Change to the fully qualified filename of your firmware file, if
# firmware upload is needed by the scanner
# firmware /usr/share/sane/snapscan/your-firmwarefile.bin
firmware /usr/share/sane/snapscan/U252V065.bin

# If not automatically found you may manually specify a device name.

# For USB scanners also specify bus=usb, e.g.
# /dev/usb/scanner0 bus=usb
# /dev/usb/002/006 bus=usb

# For SCSI scanners specify the generic device, e.g. /dev/sg0 on Linux.
# /dev/sg0

#---------------------------------------------------------------------------
# No changes should be necessary below this line
#---------------------------------------------------------------------------

#-------------------------- SCSI scanners ----------------------------------
# These SCSI devices will be probed automatically
scsi AGFA * Scanner
scsi COLOR * Scanner
scsi Color * Scanner
scsi ACERPERI * Scanner

#--------------------------- USB scanners -----------------------------------
# These USB devices will be probed automatically
# (This will currently work only on Linux)

# Benq/Acer/Vuego 310U
usb 0x04a5 0x1a20
usb 0x04a5 0x1a26

# Benq/Acer/Vuego 320U
usb 0x04a5 0x2022

# Benq/Acer/Vuego 620U / 620UT
usb 0x04a5 0x1a2a
usb 0x04a5 0x2040

# Benq/Acer/Vuego 640U
usb 0x04a5 0x2060

# Benq/Acer/Vuego 640BU
usb 0x04a5 0x207e

# Benq/Acer/Vuego 640BT
usb 0x04a5 0x20be

# Benq/Acer/Vuego 1240U
usb 0x04a5 0x20c0

# Benq/Acer/Vuego 3300 / 4300
usb 0x04a5 0x20b0

# Benq/Acer/Vuego 4300
usb 0x04a5 0x20de

# Benq 5000E / 5000U
usb 0x04a5 0x20f8

# Benq 5000
usb 0x04a5 0x20fc

# Benq/Acer 5300
usb 0x04a5 0x20fe

# Benq 5250C
usb 0x04a5 0x2137

# Agfa 1236U
usb 0x06bd 0x0002

# Agfa 1212U
usb 0x06bd 0x0001
usb 0x06bd 0x2061

# Agfa Snapscan e10
usb 0x06bd 0x2093

# Agfa Snapscan e20
usb 0x06bd 0x2091

# Agfa Snapscan e25
usb 0x06bd 0x2095

# Agfa Snapscan e26
usb 0x06bd 0x2097

# Agfa Snapscan e40
usb 0x06bd 0x208d

# Agfa Snapscan e42
usb 0x06bd 0x20ff

# Agfa Snapscan e50
usb 0x06bd 0x208f

# Agfa Snapscan e52
usb 0x06bd 0x20fd

# Epson Perfection 660
usb 0x04b8 0x0114

# Epson Perfection 1670
usb 0x04b8 0x011f

# Epson Perfection 2480
usb 0x04b8 0x0121

# Epson Perfection 3490
usb 0x04b8 0x0122

# Epson Stylus CX-1500
usb 0x04b8 0x080c