Variable Bit Rate in WMP 9 not variable?

I've tried some various settings but I think I that instead of VBR I just
get files that have a FIXED rate. Each file in an album has a different
fixed rate, but I doubt that is the true meaning of VBR. During playback
only a fixed rate is displayed.

Also, instead of smaller files I get substantially larger files. With true
VBR, files should shrink, but even simple sounding tracks result in
recordings of 70-80 kbps at the lowest possible setting.

Anyone ever heard of this?

Ava.