* Used with permission from: S.Wallis
A-Pro useful links
A-PRO Setup For Sonar (8 and 8.5)
Configuring your APro without ACT

* A-300Pro BASIC SETUP
Sonar X1a - X1D Expanded 
Preferences> MIDI Devices
inputs> A-PRO MIDI IN, A-PRO 1 and A-PRO 2
outputs> A-PRO MIDI out and A-PRO.
Then click apply

controllers/surfaces> (Click the yellow star to add a controller)
Select A-PRO from the controller/surface drop down menu
MIDI input> A-PRO 2
MIDI Output> A-PRO
* Make sure ACT and WAI and both selected.
click apply.

Sonar's main track page
Utilities> A-Pro - 1
On your A-PRO, press the ACT button, so it's lit, and press the back button (on the keyboard still) until the LCD reads Control Map. Turn the Value knob all the way to the left to select control map 0
(Sonar ACT Map) and
press the value knob to select it.
Sonar's main track page
Utilities> A-Pro - 1
If you used to use a generic controller before the A-PRO, then this screen usually has blue and green banks of knobs, sliders and buttons where you can use MIDI learn.

If you followed the above, then hopefully this screen should now look completely different. You should see the LCD screen, knobs, sliders, the pads etc... From the presets menu, select Tracks/FX/Synths/Utility 2. (I don't know why, but i find this works better than the default one, which doesn't seem to work at all for me...)

All the transport buttons on the A-PRO should now be working.
You should also notice one of the B1-B4 buttons is lit.

These tell Sonar what you want to control and you can choose from Tracks Effects Synth or Utility.

If you select Tracks, then the first 8 knobs and sliders control the pan and volume (fader) of tracks 1-8.
If you hold shift on the A-PRO, you can use the back and forward buttons (underneath the LCD screen) to have the first 8 knobs and sliders control the NEXT 8 tracks (shift and forward) Obviously if you hold shift and press the back button it selects the previous 8 tracks.
 
 

Not sure why, perhaps because I am running Windows 7 64-bit, but my options have slightly different values to yours. In MIDI inputs I have > A-PRO, MIDIIN2 (A-PRO), MIDIIN3 (A-PRO). In MIDI Outputs > A-PRO, MIDIOUT2 (A-PRO). IN order to get the ACT Control Surface to work, I have to select MIDIIN3 (A-PRO) as the input.