cannon46

i purchased a tamiyafull option king tiger and futaba t4yf controler. been a beginer modeler , i have construvted the model well and with an electronics back round found the wiring simple, problem is my kt only recoils or gun fires when it wants to?????? i have followed all instructions carefully but can't figure this out, i bought the model over a year ago so i have no come back with the seller. could some one lplease shine some light on my problem, is there something i.ve done wrong. any taughts are welcome thanks