Roland A-500 Pro Cakewalk + Ableton 9 + Fader

Hello,
my problem is that I can't connect the keyboard fader's/knobs with Abelton 9.
I did this:
I load control map 12 in the keyboard for Ableton 9.
Then I pressed MIDI on the Ableton surface.
After that I pressed a fader like "Sends" in Ableton and tried to assign 
the Ableton fader to fader/knobs of the keyboard.
 
But it doesn't work. Why?
Has anybody an idea?
Maybe my pre-settings in Ableton 9 are not correct?!
 
Greetings from Germany
 
yoshi