NES Games not playing in Game Ex

Using RockNES emulator and the games do not seem to play.  They work fine in Rock but when I launch in Game Ex it just goes to a black screen and then goes back to the game menu.  I am trying Maniac Mansion and I see the game info, art, etc.  But when I hit play it does the black screen...wait 5 seconds back to game info.  I have checked the setting in Emulator and custom menu and everything seems fine.  I can play SNES and MAME fine.

thanks,

rich