bmw 530 gear problem

ive just bough a bmw 530i auto on a c plate as it dont work
the only problem is that when you shift it into drive or 1st 2nd 3rd nothing happens but if i put it in reverse fine it works and moves
has anyone got any ideas ?????
i am thinking its maybe a switch on the gears
gearbox and torque converter is fine and tested

cheers
rob