While DJ makes a great point that doesn't help you now. The reason your getting that error is cause one of the behaviors has written incorrectly. If you behaviors properly look in the code and find the problem.
I'm not a coder by any means and nether was Creative Insanity! But there is nothing I or CI couldn't do using behaviors. However I did take dj's advice and learned about coding so I knew both sides.
That error comes from using a session. Possibly MM_Username issue.