Sleepweaver Advance leaks badly (new mask for me)

[Alaskamike]

I've been using a VPAP for several years, and I was using the Wisp nasal mask without a problem (other than that I turn in my sleep and it would break seal when I turned). I started using a Sleepweaver Advance a month ago. I can get it to seal when I first out it on, but during the night it starts leaking - to the point that I take it off to get back to sleep. At first I tried to keep the straps as loose as possible while maintaining a seal, but I've started tightening them up to try and get through the night - without success. Am I doing something wrong or should I just go back to the Wisp?
Thanks.

Mike