Volume problem. My aftermarket Pioneer car stereo keeps changing the volume to zeo?

As soon as I change the volume to say 20, it just starts going down till its a zero. Over and over, its been acting a little weird lately. I just put 2 new speakers not long ago, could this be part of the problem? It did work and play after i put the speakers in... Thanks...Volume problem. My aftermarket Pioneer car stereo keeps changing the volume to zeo?it is a problem with the volume button. i had a similar issue with my pioneer deck. except my volume went all the way up every time!!!