Newly installed CD/DVD drive not working

I have a late 2011 Macbook Pro. My CD/DVD drive recently stopped reading discs, so I bought a refurbished one. I carefully followed the ifixit directions and installed the drive, but it does not respond at all. The old one accepted discs, but made noises and ejected them. The new one doesn't even accept discs, and I haven't even seen evidence that it is getting power. I did notice that the drive I ordered is for early 2011 models and my Macbook is late 2011. I don't know if that makes a difference. What can I do?