WM (Windows Media) Encoding problem

[ahmdprog]

Gentlemen,

I am trying to transcode Video Content to WM Encoding and transmit to the public internet.
When I configured as the following

:sout=#transcode{vcodec=WMV1,vb=64,scale=1,acodec=wma,ab=64,channels=2}:duplicate{dst=std{access=mmsh,mux=ts,dst=192.168.0.1:1234}}

It is working fine, even when I am changing the video bitrate to 32 or 96 or 128.
But, when change the Audio Bitrate to other than 64, then audio will not be heard at all.
I tried to play it using Windows Media Player, but the audio is working fine, only when it is transmitted with 64k bitrate.

Please can you help me on this and tell me how to minimize audio bitrates lower than 64k.

Many thanks in Advanced.