Wireless does not work

I just got 2 sets. I put together the box bot. It works fine when tethered, but the radio controller doesn’t make it go. Do you have and tips? I went through the book twice and rechecked hookups, etc. I tried the second transmitter and it didn’t work either.

**Be sure the crystals are installed on both the Transmitter and the Receiver and verify they are both on the same frequency. Also you should only have 1 Transmitter “ON” at a time if you only have the Starter Kits because all Starter Kits should be on the same frequency. More than 1 Transmitter “ON” at the same frequency will cause interference. Also, any one of the following could be defective, although it is unlikely: Transmitter, Receiver, Transmitter Crystal, Receiver Crystal, Receiver Cable, or the Vex Controller. Swap each one of these items with the same item from your second kit to see if you can isolate the problem to one component. **