I made a pot call this week (glass over aluminum with a walnut pot) and it sounds flat. There is no rollover at all. I've tried a half dozen strikers and none work well. I've made a few dozen pot calls in the past and never had any sound like this one. What could be causing this?
Not knowing your design and specs, it's hard for anyone to tell you what's wrong with your call. However, I have found, if you have a ring pedestal design that is not vented, it will be very flat sounding. It's also possible that you have a poor glue up on the soundboard or surface, or both.
Did you drop it?
If you turned it all at once it most likely cupped.