facetime

I just bought the facetime app, my brother is on his new iphone & I am on my imac. It worked perfectly except the second time we used it, he could not hear me on his end but I could hear him. He was checking his volume controls & when he muted on his end it muted him but he still could not hear me when he unmuted on his end.......
Not sure what the problem could be, I read that some other people experienced some of the same problems & could use some advice.
SO COOL otherwise, but I would like to hear him......then I would definately give it 5 stars!

bbiilliiee about FaceTime, v1.0.2