Review on American Shifter 60251 Automatic Transmission by Aaron Ethridge

This derailleur is not shifting properly, it is skipping detents on each pass of the derailleur. I spent countless hours tweaking and tweaking it and finally just uninstalled it. I called American Shifter and they said I probably had it set wrong so I had a mechanic work on it for 4 hours and he couldn't get it to work properly either. American Shifter said to return it but I don't know who the seller was, all I know is that I bought it from Revain. you can help me