That doesn't look like a valid propertyChange event script for Vision. You aren't checking the event's propertyName--that is mandatory. Also, please format posted code as code, so indentation is preserved: Wiki - how to post code on this forum.
You don't have enough .parent references to get to an outer object. Also note that there is a quirk of Vision that prevents the proper jython wrapper being applied in this case--the simplest fix for that is to install my Integration Toolkit. Without the fix, a custom property like .ActiveStepDate won't work.