Imac G4 built in audio mic is not receiving

Hello all,

any ideas

Finally upgraded my imac from 10.3.9 to leopard 10.5.8 and put in garageband 4.1.2.

I went to start using garageband and have been unable to get a signal from the built in mic. I checked to make sure that built-in was the option chosen on both my system and gband preferences.

I attempted to get signal on a song from before the upgrade (I was using gband 1 before) as well as a new project, both to no avail.

Any ideas greatly appreciated.

Thanks for your time..