Pioneer XM Radio Problem

I have installed a Pioneer (DEH-P3700MP) head unit and Pioneer (GEX-P910XM) XM unit in a 2005 Chevy Surburban.  Everything is hooked up correctly, and my customer has already turned on his XM service.  I have gotten past the challenge of turning on the AUX fuction on the head unit, but for some reason I cannot get the SAT Radio channels to show on the head unit.

I have pressed the clock button to select the channel as indicated in the operation manual for the head unit, but nothing is working.  In addition, I had the customer confirm that their SAT Radio service is on.

Any suggestions to fix this problem.  Thanks in advance.

check to see if there is a reset button on the xm unit and the radio itself.   

i dont think you need to enable the aux input to make that unit work,  that may be your problem right there.