I had this problem too, but my regulator maxes out at 200. I upped it to 20, and I don't have any more problems. If you switch out propane tanks, and it still doesn't work, you may need to get another regulator like rightbrainbeads says. One of the "guys" offered to sell me a BBQ regulator that may help. Here's a link to the thread I started on this topic:
http://www.lampworketc.com/forums/showthread.php?t=3773
Good luck!