Cannot add LDAP domain users as SSO administrators

In vSphere web client 5.5 under Users and Groups I select Groups for SSO administrators group.  I click to add a member under Group Members

In the Add Principals window I select our LDAP domain and then select and add a user from the Users and Groups drop down menu.  I  click Check Names

to verify the username is correct.  But now when I try to add the user to the SSO administrators group I get the following error:

Add Principals:  Not allowed: user @ ldap_domain objectId is null

I'm not sure what is causing this has anyone seen this error before?  What was the solution?