DO YOU HAVE AN 'X2' transponder?? **UPDATE FIRMWARE** or it won't work.
Regarding transponders- im not absolutely sure how it works as I don't have one, but over the weekend that some people got to Canada heights and their transponder didn't work. They needed to connect it to their computer and update firmware EVEN if their subscription was still valid....
Can you make sure you're up to speed and up to date with yours well in advance of sunday please?