If your IaaS server is on Windows 2012 then you may need to disable TLS1.2 - you may have reviewed this already but in case you hadn't:
vCAC 6.0.x with Windows 2012 Guest Agent “stuck” Looping with “wait.vbs” script | Cloud Relevant
http://vmwarevcloudvirtualization.blogspot.ie/2014/04/vcac-agent-ssl-issue.html
VMware KB: Connecting the guest agent to IaaS on Windows 2012 fails with the error: Client certifica...
