» Certificate does not correspond to private key

I copy and paste the keys I used on my Zimbra cluster (wildcard cert) and they aren't working.

I get the following error when I put in the server and private (CSR)keys:

I got my cert from NameCheap, which gets it from Comodo. I tried a few combinations and nothing seems to work. I used a 2048 bit key for the CSR if that makes a difference.