Mute not working on Cubase 8.04 with OB

I’m using OverBridge with Cubase 8.04 and I can’t find out how to mute sounds. If I click on the mute button I still can listen to the sound. The only way is to lower the level of the oscillators manually. Can you help me?
Furthermore I have another problem. I can play the sound on the first track from my Korg Minilogue , which I’m using as master keyboard, but I don’t understand how to play sounds on the other tracks. (I’ve setted Midi tracks in the following way: track 1 - Midi channel 4 ; track 2 - Midi channel 5 ; track 3 - Midi channel 6 ; track 4 - Midi channel 7.