sphI know it's been a while and you might not see this reply, but in case you do, is there any chance you could post or PM me a screenshot of both 1) your MIDI config in FL Studio (like the first screenshot I posted) and 2) a typical MIDI assignment on the A-PRO editor that works for you (say you're trying to map the first slider to something). That would be much appreciated.
sph

You're looking at it already. And sorry, I don't use FL Studio. Sonar X3, baby!
The screen shot above is what I would see when assigning a knob or slider to output CC data for my needs. "S1" as shown above is "Slider 1." To output CC, I assign it to Channel Message, set the type to Control Change (CC), set the controller number to let's say "50," and finally set the min/max values to 0/127. I click OK. And when I am all done building my control set, I
transmit the Control Map to the A500-Pro keyboard. You must transmit the map to the keyboard, otherwise no changes will be saved to the keyboard as sliders/knobs are configured. On the main editor screen, transmit is in the Communication drop-down menu.