I think you emailed already, but just in case.
The most common mistakes in this area are the First Digit being Set wrong on your Xxtra. There are Two Rows on the First Digit, you need to use the Bottom row for Airtronics.
Also, the Receiver "Input Harness" being plugged into the ESC backwards, or to the receiver backwards. The ESC case is marked, and the Black wire should go to the Outside Edge of the Case on the receiver.
Send us an email if you have not done so yet.
Novak Electronics Tech Support