Reply to Mapping Problems

Hey guys; first off I hope this post isn't being re-posted but I searched the community s and even Google to help me solve this problem but to no avail. I'm just getting into mapping in Traktor Pro 2.5 and I wanted to map multiple functions to a button so I tried to "create" the modifier but every time I press "shift" the program doesn't learn it...it remains as "n/a". I don't understand why this ONE button cannot be learned (I'm referring to the actual shift button on my midi controller). When I DL pre-made mapping...the shift button works fine as the modifier; Also, I can make the program learn any other button to be the modifier except shift...:S I really don't understand why it wouldn't even be registering in the software. Looking forward to some help guys, thanks.
P.S Like I said the shift button works with pre made mapping and the LED works etc So I know the button does indeed work.
Oh I'm using American Audio VMS4