My Homelink does not appear to be working. on 2008 Audi TT

I had a new garage door openner installed and cannot connect my car's Homelink to it. When I press the I and III buttons, nothing lights come on, nothing. I have tried it several way, with the car started, car turned off, key in starting position...and nothing. Any suggestions? Thanks.

Asked by for the 2008 Audi TT