That's strange. Something similar happened to me. I was testing versions 0.10 and 0.11 of the emulator, but I noticed that Tekken 4 and Tekken 5.1 have a bug where, even if you insert the credits, the game doesn't subtract them and doesn't set them to 0. It must be an emulation bug, but it only happens with those games, since I tested Vampire Night and it subtracts the credits correctly.