Auxiliary heating timer control

My car is a 2007 E320cdi. It has the auxiliary heating system fitted. I can start the heating system using the centre console manual switch, also it activates from the remote control fine. The problem is activating it from the dashboard timer control. I can program in a time for it to start, the orange light on the manual switch comes on, indicating the system is programed. When the time comes to start the heating system, the orange light goes out (as it should according to the manual), then the red light should come on to tell you the system is activated to heat. Problem is the red light doesn’t come on & nor does the heating system. The dash display changes from the time display that it was programed to switch on, to “Timer off”.
Could any of you offer any advice as to what is wrong, or if I am doing something wrong. Or is it something that may need adjusting or activating on Star.