Attempting to Export Private Key fails with Ambiguous name error

I'm working throught he instructions on how to export a private key in the event someone loses their Outlook encryption keys.  I'm at the point where I'm trying to export to a blob file.

certutil -getkey 5xf1617d000040000034 outputblob

I get the errors:

CertUtil: -GetKey command FAILED: 0x8002802c (-2147319764)
CertUtil: Ambiguous name.

I'm using Win 2K8 R2 and have it clustered to share the same DB between two servers.  I'm figuring the problem is that when certutil does its thing it comes back with the active CA's hostname and the shared cluster name. 

Is there a switch in CERTUTIL that designates which CA name to use?

David Jenkins