From your description, it is hard to tell what's going on. I think you are saying that you can only command servo #1 and not #2. Right? An O'Scope would be very helpful but even without one you can solve this probelm.
Have you written a very simple program to test out the hardware? No serial input, just command one servo to go left, pause 2 seconds, go right, pause 2 seconds then center for 2 seconds and then repeat. Then do the same with the other servo.
If that works, then verify that your serial input is working correctly and you are actually getting valid values for the 2 variables.
In general, you should decompose your problem into smaller problems to isolate the location of the defect. Follow a logical progression and the solution will become clear. claro?