Wall Worm Forums

I need help please. After using wallworm several times, I'm intermittently having difficulty with the collision model not working (please see attached). I'm choosing concave and all the other suggested settings, but something has to be off. I've tried auto hulls, custom hulls, hull helper etc etc. Using max 2016 and latest version of wall worm. Is it hit and miss or should i be splitting up this door frame example into three separate models? Sometimes it works magically (with the exact same steps/settings), so it's very frustrating when it doesn't for hours and hours on end.