12864 LCD issue

Working on my first 3d rpinter build but I've run into a problem. I ordered one of the larger LCD screens 12864 from Folger Tech and I'm having issues getting it working.

I have tried a couple of different firmwares I found online and one the I created myself (here is the link:[www.filedropper.com]).

The screen comes up and displays just fine. I can use the button to get to the menu but I can't scroll using the dial.

Anyone have an ideas of how I can test this issue?

Thanks

try swapping the cables, this will at least tell you is the cables are good... maybe. I just received 2, one works fine the other has display contrast issues.