There is no "MIDI Learn" button in the Device Control Map window

My system info: Microsoft Surface Pro 3 - 128GB, 64-bit OS, x64-based processor

I have my Axiom 49 2nd Gen controller connected to my AudioBox USB with a dual MIDI cable (in to out, out to in). I'm able to hear and see instrument/VST signals when I press on the controller keyboard keys. Yet when I open the Device Control Map window and choose the Axiom, the "MIDI Learn" button is non-existent. Looks like this:

My current External Device Configuration looks like this:

Input

Output

Thanks in advance.