I see one of my paid app frequently going into top 200 Trivia paid app category in US app store but I don't see any sales next day. Also not in Gross pay category. Is it possible? People are downloading without paying money.....
To get into the top 200 in the trivia category requires very little downloads a day. Are you seeing any downloads? If so, that is probably the amount you would expect for being around 200 in the trivia category. Then again, there are ways to download them free...
To be more precise, IF people are getting the game for free (pirating), it won't show up on the App Store rankings since they aren't using the App Store. My guess is that the paid Trivia section is so small and you're far enough down that you're seeing fluctuations based on the game's history more than current sales.
Is it this one? That's just Apple resetting the rank daily. The same pattern appears on other games around your ranking (You 4 Prez, Guess the Logo). For that matter, Smarter Than Pre Schooler? shows the same behavior, so I'd guess that's not selling either.
Then my best guess is that you are tied for last with a bunch of other apps that aren't selling either, so when Apple computes the ranks for the daily rank listing, it has to use other criteria for sorting them. On a more general note, it appears that either a: trivia games don't sell at all, or b: a well crafted one would get into the top 100 easily, if not top 50. I looked at a few of the top selling ones, and they are stuck to the top of the list with little variation from day to day.