Playing over drum track troubles..

Hey guys

Hoping for some help… new to mpc beats so hopefully it’s a simple fix.

I’ve got a drum track but when I go to add a bassline using either “key group” or “plugin” I can’t hear my drum track..

I’ve checked that nothing is muted.

Also if I add a bass to “plug in” it just plays the beat but in bass.

Any help would be much appreciated.