rack and pinion mate acting weird

hi all

my name is amir levy and i am an aerospace engineer working in israel.

i have recently started design on a machine with some mechanical mates and have encountered a strange problem.

while using the "rack and pinion" mate i noticed that after mating, the parts dont move as intended.

instead what happens is the following: when i rotate the pinion the rack is going back and forth instead of just one direction. and the same happens when i

slide the rack (the pinion rotates back and forth).

does anyone has any idea what could be causing this?

thanks in advance