I keep getting the GFCI breaker tripping after wiring my hot tub.

I wired 2 hot Red and Black to the proper terminals and the White to the neutral and the Bare Copper to the ground Post at the tub. I am using 6-3 w/G per instructions. Could the GFCI breaker be bad? When
I wire without the GFCI breaker in the line everything works... this is using a 50AMP double pole breaker at the main panel.


HELP!