Mike,
Ok, I have tested PCStage with the CaptureLevels plugin, and I have found that it does not work with Capture 2005.
As the date modified on the plugin is 2005, I tried it with Capture 3.0.31 and it does work fine. This led me back to try the Capture 2005 CITP Compatible Mode, but this still does not work.
I can only suggest that you go back to the authors of the CaptureLevels plugin and ask them to take a look at updating it. I do not believe there a reason it could not be made to work.
Regards,
Paul