Homelink problem

Hey guys, Just bought an A4. My homelink works when it feels like it. I succesfully programmed it and when the lights flash it works fine.
However sometimes the lights wont blink at all. Took it to the dealer twice, had new visor installed, they checked the connection and ground and everything checked fine. Still doing the same thing. Any ideas what might be going on?

Is the car on when you try to open the garage door? It will not work if you don't have the car on.

yes, the car is on whenever I try to use it.