Help!!!! Video Card Problems?

Ok, so I wanted to switch the video card in my computer to my other computer. I removed it and tried to install it, but for some reason it won't fit, even the the computers are basically the same. I was pissed about that, but whatever. The problem is, now I'm trying to put it back where it was, and it won't go back in!!!!! Help me, please!!!!!!!|||If it is PCI-express, you an try slotting the back part of the card first, making sure all the other pins line up. Then gently push the rest of the card down until there is a satisfactory solid feel to it (if you know what I mean)|||I am guessing that the retention latch on the graphic card slot is in the wrong position. Try to release it. The latch is located on the far end of the slot (the side that is closer to the computer's front panel).