I am having the same issue and mine is stunnel on centos 6.4 with zpanel for webhosting provider as i heard you can use them side by side by the zpanel website i've tried uncommenting the lines related but it doesnt fix it everytime i run service ajenti restart it claims it was not running and starts it but repeating the proccess yeilds the same result so i know its crashing im going to try the beta and see if that work unless you have a simple fix?

update:

i tried following the install directions but it only has this version installed

Package ajenti-0.99.20-1.noarch already installed and latest version

specific ending of ajenti-panel -v 

15.07.2013 00:10 core.py:107  ERROR SSL tunnel failed to start
15.07.2013 00:10 core.py:112  INFO  Starting server on (u'0.0.0.0', 8000)
Traceback (most recent call last):
  File "/usr/bin/ajenti-panel", line 86, in <module>
  core.run()
  File "/usr/lib/python2.6/site-packages/ajenti/core.py", line 115, in run
  listener.bind(bind_spec)
  File "<string>", line 1, in bind
socket.error: [Errno 98] Address already in use