Sound input jack in OS X ??


Has anyone else had difficulty getting any sound to pass through from the input jack on the back of their Mac in OS X?

I use mine for things like transfering sound from audio cassette to aiff or other computer formats, so this is kind of irritating for me.

Under OS X I have been unable to get it to work.

I've tried using Sound apps like 'Sound Studio For OS X' and they don't seem to be receiving the sound from the input jack. If I reboot back to OS 9.1, the OS 9.1 version of 'Sound Studio' has no problems receiving input from the sound jack on my machine .

This is the only thing that's currently bothering me about OS X (other than not having a driver for my Agfa scanner yet -- but I can understand that at this point!)

My system:
G4 450 MP, 512 MB, two 20 GB HD, Radeon graphics.