LDAPS with AD Server 2008R2 certreq -accept fails

I'm having the issue listed here: Active Directory SSL Certificate Private Key Not Attached

however they don't explain what to do to fix the private key not attached if the certreq -accept fails.

I'm using an external CA, and I can import the certs just fine via the GUI.

certreq -accept certname.cer returns the following error:

certificate request processor 
cannot find object or property 0x80092004 (-2146885628)

Googling doesn't seem to find anything related to my problem, most links are about IE9 or SQL server which don't seem related to AD LDAPS to me.

Anyone know what the problem is? And how to fix it?