Can you describe the process you are using, in detail, to desaturate with the adjustment brush? Are you seeing adjustment pins on the image, but no effect? Please provide more detail.
Sorry for the issues with adjustment brush in Lightroom.
Can you please post a screen shot of your Lightroom windows before using the adjustment brush and after using the adjustment brush.
By the way if you can not see any adjustments at all try calibrating your monitor.
Temporarily turn on the mask overlay to make sure you are covering the desired area.
Check your "flow" and "density" settings to make sure they are high enough for the effect to be seen.
Thanks, everyone! I appreciate the willingness to help out, believe me.
In the end, I was not sure if it was a software issue, so I just opted to upgrade to the CC. It works like a charm now. The good thing is that all of your questions/observations made a difference when I started using it in the new version of the software.