Stay off of the backplane.
Does it have all the cables ? Is the cascade cable in place ?
I have seen frequently blades for sale that used to be in a machine in cascade (2 or 3 or 4 blades ganged together ) They sell the blades individually but don't plug in the cascade cable and they don't have the default cable. At that point there is no communication possible and the card won't be detected.
look at the side of the card. there is a hole in the card with 5 connecotrs (like 20 pins connectors). on is angled the others are straight. there should be a short ribbon cable going from the center to the one labeled '1' . if that i smissing : bingo. there is your problem.
to gang cards together you string the cable from the center , through the hole to '1' of the card above. the center of the second card goes to '2' in the card above and so on... if you use the card standalone you must create the 'patch' locally to yourself.