Hi there,
Try
this little document, that details some of the more technical steps you can look into to solving this problem.
I'd recommend tethering your controller and your cortex to allow them to sync and to perhaps reduce the middle-man to help you figure out the error.
Additionally, head over to vexforum.com and post over there as well. There, I think you'll find help from a more focused community and even VEX technical staff.
Hope this helps,
- Sunny G.