Abls1-
OK, so you can run a game from the command line outside of AM fine ? When you try to run a game in AM, what error do you get when you exit AM? If, everything else is correct then you have something wrong with your romlist.
Step one, make sure you have the correct romlist selected under display/emulator. If that is correct then check the romlist and make sure the rom names match what you have in your rom folder. Otherwise try deleting the romlist and creating a new one.
Also, did you generate a romlist or import one? Again, check the romlist and make sure the names match.