I'm working on a B2B project and am having some SSL issues. Or should I say our partner is having issues with our SSL cert. We've got an SSL123 cert from Thawte that we are using successfully with other B2B partners in both our test and production environments. I'm working with a new partner and they are telling me that the cert I gave them (I exported our cert in P7B and CER (DER) format) isn't "chaining up". This is in reference to the CER format cert. He says they can't use the P7B cert with their software. My knowledge of SSL and certs is limited but from what I can tell, CER files don't have the entire cert chain in them. He says that he's installed the root and intermediary certs from Thawte but our cert still won't "chain up". He's suggesting we need to buy a different kind of cert from Thawte. This is all beyond me... any insight?