iPhone 5 Ear Speaker not working - Earspeaker 100% OK

Hi Experts,

i have trouble with a IP5 with the Ear Speaker.

Everything is working but the Ear Speaker will not give out any noice.

I tried out the hole LCD with Speaker, Cam etc. and so i can say it work 100% on an other Iphone.

The flex and eveythink is working correct.

Anybody an ideal what else could it be?

I was thinking about the dock connectorbut not sure don´t have a part to check it out.

Thanks for any help.