i have a 1994 e420 mercedes benz that wont go into reverse on 1994 Mercedes-Benz E420

all the other gears in the transmoission work except the reverse gear... what could be the cause of thgis problem??????

1 answer
What's the fluid look like? Does the shifter go into reverse but the car will not move? Did this just happen or has the transmission been slipping for quite some time now?