Exception, 'Unexpected status code: 400'

Good afternoon all

Im getting an Exception, 'Unexpected status code: 400' error when trying to add a host to my vco installation.

Host:  vCenter IP

Port:  443

Secure Channel is checked

Path:  /sdk

Session Per User (I've also tried Share a unique session)

Domain:  corp.domain.com

Connection Test = Success

Username/Password = Same used for connection test.

Im running VCenter 5.1.0 and vCO_VA-5.1.0.0-817595

Any help would be greatly appreciated...

Graham