Install of Tacker on Ubuntu14.04

Hi,
I am studying the NFV and interested in Tacker project. I want to install and use Tacker in order to understand the function of VNFM and NFVO. I install the tacker with the document description of Tacker Install on the Ubuntu14.04. But i face some problems as follow:

The error information:
2016-01-23 08:18:27.998 | Directory '/opt/stack/nova' is not installable. File 'setup.py' not found.
2016-01-23 08:18:28.169 | You are using pip version 7.1.2, however version 8.0.2 is available.
2016-01-23 08:18:28.169 | You should consider upgrading via the 'pip install --upgrade pip' command.
2016-01-23 08:18:28.189 | + exit_trap
2016-01-23 08:18:28.189 | + local r=1
2016-01-23 08:18:28.190 | ++ jobs -p
2016-01-23 08:18:28.211 | + jobs=
2016-01-23 08:18:28.211 | + [[ -n '' ]]
2016-01-23 08:18:28.211 | + kill_spinner
2016-01-23 08:18:28.211 | + '[' '!' -z '' ']'
2016-01-23 08:18:28.211 | + [[ 1 -ne 0 ]]
2016-01-23 08:18:28.211 | + echo 'Error on exit'
2016-01-23 08:18:28.211 | Error on exit
2016-01-23 08:18:28.211 | + [[ -z /opt/stack/logs ]]
2016-01-23 08:18:28.211 | + /home/huangyongyuan/devstack/tools/worlddump.py -d /opt/stack/logs
2016-01-23 08:18:29.337 | + exit 1

but the version of pip is :
huangyongyuan@ubuntu:~/devstack$ pip --version
pip 8.0.2 from /usr/local/lib/python2.7/dist-packages (python 2.7)

so i am confused and don't know how to install tacker.

can you tell me what problem happen or how i can install it correctlly.

I am looking forward to your reply. Thank you for your consideration.