If you can’t manage the private key, you need to have you Security person grant read access ot the account in question, if they can’t, I suggest re deploying the certificate to the personal (my) area instead under local computer.
I think if you don’t have the little ‘private key’ icon on the top left of the icon, you don’t actually have the ‘private’ key with the cert.
When in doubt, you can simply generate a self-signed cert as a test and you’ll see what i’m saying is true 