pkg_resources.DistributionNotFound: Pygments

[Fatalerr]

I installed markdoc successfully in a Debian server, but failed on running markdoc command. it report below error:

root@aFEWS:~# markdoc
Traceback (most recent call last):
  File "/usr/local/bin/markdoc", line 5, in <module>
    from pkg_resources import load_entry_point
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 2707, in <module>
    working_set.require(__requires__)
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 686, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 584, in resolve
    raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: Pygments

My server environment:

• OS

    root@aFEWS:~# uname -a
    Linux aFEWS 3.2.0-4-amd64 #1 SMP Debian 3.2.63-2+deb7u1 x86_64 GNU/Linux
    root@aFEWS:~# python -V
    Python 2.7.3

• python installed pkgs:

root@aFEWS:~# pip freeze
ansible==1.8.2
chardet==2.0.1
CherryPy==3.6.0
ecdsa==0.11
fpconst==0.7.2
Jinja2==2.7.3
Markdoc==0.6.6
Markdown==2.5.2
MarkupSafe==0.23
paramiko==1.15.2
pycrypto==2.6.1
Pygments==2.0.2
python-apt==0.8.8.2
python-debian==0.1.21
python-debianbts==1.11
PyYAML==3.11
reportbug==6.4.4
SOAPpy==0.12.0
WebOb==1.4