Hi, I'm new here and I just brought two zip-zap r/c. I brought a Mazda Savanna (charges fine BTW) and a 1997 Toyota, the Fast and the Furious edition. They work fine if I try using one at a time, but when I try to use both, the Supra doesn't work. Can you tell me how to fix this problem? I know that I can adjust the frequency on the Mazda, but can I adjust in a way so the Supra and the Mazda can race at one time? Please no flame about buying a 1st generation, if that was what I brought. Thanks in advance