Need to install GFCI for pool light

[coachhim]

I have pool light that has a transformer on it. Inside my breaker box the switch for the pool light has 2 wires white and black in the breaker box that’s installed in the old breaker.
The breaker I installed keeps tripping . What am I doing wrong??

 

[ajw22]

You probably did not move the light neutral to the GFCI CB neutral connection.

Show us pictures of your CB and wiring.