[Dave Flowerday]

You're not trying to use an old OI by chance, are you? OIs from previous years won't link up with the new RC.

Most of this has already been mentioned, but:
- Swap out all the cables one by one to make sure it's not a bad cable
- Any difference between running it with a tether versus wirelessly?
- Is the OI unplugged from the power adapter when you're tethering it?
- Is the robot's battery sufficiently charged?
- Relays and speed controllers from last year should work, but I'd try unpluggging all joysticks from the OI and all inputs/outputs from the RC to try to eliminate a problem there
- When using the radio modems, are the LEDs lit up? The transmit LED on the OI should be flickering
- Along those lines, try a different radio channel to make sure it's not an interference issue (directions should be in the IFI manuals)

Let us know if you make any progress...