Gimbal control with the main sticks (ch3 and ch4)

Hello all! I’ve made a stand along gimbal unit using a simplebgc tiny and flight controller. I want to be able to control the tilt and pan of the gimbal with my main sticks. What is the best way to do this with params? As is I can’t get it to actually move the gimbal with ch3 and ch4, even though I see RC input on the gimbal controller. If I use the wheel on my controller that is set to ch13 it works. Any idea what I’m doing wrong?