Megadrive key mapping

[alex13]

Hi,
i have built a arcade with gpio controllers. Unfortunately the megadrive emulator is not working correctly and i do not know what's the problem. The game prince of persia starts correctly. When i push the start button the game starts but the game is in pause mode. When i hold the start button the game is unpaused but it will pause again as soon as the start button is released.

Same problem with other games. In other emulators all buttons are working fine.

Any hints would be appreciated.

Alex