FaceTime - no sound

[Pommier]

Been trying FaceTime with friend. I can hear and see him fine. He can see me, but not hear me. There's a button on the screen that looks like a microphone with a slash. Touching it makes it either black or blue, but has no effect on his hearing me. We get the same results whether I call him or he calls me. Can anyone help?

 

[Tim SPRACKLEN]

I've moved this to the Help section.

Tim