Please help..R129 aircon vent problem..

Guys i hope you could help me out..

When i press the directional vent buttons on my climate control push button assy...nothing happens to the airflow, even if the indicators on the button light up!

the airflow remains constant coming out of the center vent and the vents on top of the dash only..

another problem is with the center vent, the thumbwheels that control the opening and closing of the left and right passenger vents dont seem to be working!!

car is a 1992 300SL please help..