[digitalradio] No audio from soundcard

[mac2251]

I have tried everything I can think of and cannot get the 746 to
transmit.  The audio from my speakers sounds perfect with no
distortion etc, but no transmitting.  The card is the computer card
Realtek and I also tried with a USB external card, still no luck.  Am
I missing something here ?  If anyone has a solution I would
appreciate it.  I might add the system was working perfect until about
a week ago...Thanks  Mike  K9HCK