Why does my volume keep going to zero?

A

AC Question

Volume keeps going to zero

I have an S5 with the official S5 case, just about every time i look at the phone the volume is a zero. I thought that i was catching the volume keys when the case was closed. I tried this but it was not that, in fact the phone closes when the cover is closed.

I can't see anything i have changed or could cause this, i have missed various calls and texts because of this.

Can anyone shed some light on this for me