Problem with program changes

Hello

I have problems for a long time and still in Cubase 7 : when I have program changes inside a track, Cubase send this PC even the track is muted.

The problem is when you have many tracks with the same midi channel, there is bugs…

Why a track sends informations when it is muted ?

How to change that.

To complete, I can’t use the program change ability of my Nord Wave because it bugs the synth when I have many tracks for him ( same midi channel, different PC ).

Thanks for your answers