How do I update a tune after changing a gear ratio? (I haven't,just thinking about it)

I have an unlocked PCM and a Trinity, for a Ram 1500 six speed auto. The device will save the stock tune, and then when I upload a tune, the loading screen goes all the way to 100%,I cycle the power as instructed on the screen and it looks like its about to work, then it shows that the tune failed ...