2002 Audi A6 DRIVEABILITY PROBLEM

2002 Audi A6 6 cyl Front Wheel Drive 130000 miles

Lack of compression Bank 1. Back cylinder shows no compression the other two 60 pounds. Bank 2 shows 180 pounds on all three cylinders. How can I confirm cam timing? The timing belt appears to be tight & in good condition. Ihave the timing mark lined up on the crankshaft pulley and the valve cover removed on bank 1. So far I have'nt been able to get a diagram showing the timing marks for the camshafts to see if they are out of time.