I have 2 x HTC One (m7), MHL only works on one of them and not the other?

[Lee8889]

I have 2 x HTC One (m7), one of them i bought in the uk and works no problems connecting to my tv. The other i bought recently 2nd hand in Australia (living here atm). The phone works fine, the usb port charges etc. but when it comes to connecting to my tv, nothing. I have a hdmi to mini usb adapter, so i just plug hdmi cable from tv to adapter, mini usb to phone and connect adapter to power source. When i connect the cable to the phone it recognises the connection as it starts to charge, but no MHL connection like my other phone. I cant figure out why it wont work. As far as i know theres no app required for MHL to work?

Any help would be greatly appreciated.