Can't hear sound post plug in

[Francis]

 I am able to hear my guitar but for some reason, it does not let me hear the guitar signal post my plug in. I should be hearing a distorted guitar sound, but I am only hear the clean sound. I can see the guitar signal drive the volume meters I=on my plug in, and on the Jam Kazam app, but I don;t hear the distorted signal. 

Advice would be very much appreciated!

Thank-you

Francis