Do you have a remote for the HU? I have a 985, and went through this the other day. I had previously had the iPAQ plugged in, but it was a while ago and had forgotten (the shame )...
Anyway, if you select the input (AM/FM/CD/AUX) on the panel itself, it selects the RCA inputs on the back, If you select 'source' (ie scroll through) from the remote, it selects the 1/8" jack on the front panel.
If you've tried this (or the 980 is different), I apologise for telling you how to suck eggs.
But I hope it helps!
Perhaps you can help me in return: have you tried to 'remote' the face away from the head unit?