My best guess would be to make sure that your interface settings are set up.
(I use a M-Audio FireWire 410 and the audio driver is a seperate application on my computer).
Second guess would be to check what your output is on Logic. Chances are that the settings are correct, but it's worth a shot.
Wish I could be more of a help! But it's hard troubleshooting from a distance.
Let me know if this helped!