I hate to ask it.. but I had this type of issue and it ended up being a firewall rule on the ldap side. You might want to run a ldapsearch -x for the destination to confirm everything is ok. Once you confirm everything is ok and firewall is working then you have to take a look at the vcloud director logs... it's normally some type of bind issue.
If both methods don't produce anything then I am afraid vmware support is the easiest path to solutions.
Thanks,
J