voice not beign transmitted

On my server, some clients get in and connect fine, but no one can hear
them, and Mumble doesn't act like they are trying to transmit. IE, if I
were to hit a push to talk, it doesn't indicate that they are talking.
They can be heard on the local loop back and with the audio wizard. I
was wondering if anyone found a steady solution to this problem.

Thanks.
--
Libere,
Pascal Diogo Antunes.

"Tous les animaux sont égaux, mais certains sont plus égaux que
d'autres."- George Orwell.