mpd24 fadders and nobs wont work help please

I have my mpd24 hooked up threw usb and i have all these correct midi settings. When i try to asign control of a fader in ableton with a fadder on the mpd nothing happens...

actually when in midi asign mode in abelton nothing shows option to asign when i press anything on the mpd.

My keyboard midi controller works fine but only has two nobs.

anyhow if anyone could help me out..

thanks
pk1