My Modifry DCI works great with my alpine hu, but mute doesn't work. Am I missing something?

 

The Modifry DCI supports two different ways of muting. For headunits with a hardwired TEL/MUTE function,
(from the prehistoric days when cell phones were built into cars and you wanted your headunit to mute
when the phone rang), the command can be sent along this wire. The DCI can also send a mute command as
it would any other command (the equivalent of hitting the mute button on the remote or faceplate).
Which way the command is sent depends on a dipswitch setting on the DCI. My guess is your headunit lacks
the hardwired mute, but the dipswitch is set as though you have it.
The other possibility is that the car's mute circuit is blown, which apparently would be shown by the green
light on the switch being lit all the time, regardless of button position..