RC Truck and Construction - radio setup help!!!!

ok i upgrade my radio from a flysky 9x to a tactic tt650 in my track loader
but im using a mangom hrc setup so the pump can't run all the time. so im trying to mix the pump so when i move channel 1-4 i drives the the pump one way. but i cant seem to get it to work. i have the pump on a three point switch
and mixed. but the pump esc wont set it just beeps and wont will only if i move the sticks up not down. any help please!!! i don't want to run the 9x because it is old and doesn't keep setting anymore, and have to re-setup my models every time i turn them on!