So do you see even the vcenter server listed when you logged on via the web client? permissions maybe (though unlikely)
For the vsphere client are you ticking the "use windows credentials" box? if so you might run into issues with SSO
Try the following:
1. Login to SSO, via web client, using admin@system-domain user.
2. Under Administration > Sign-On and Discovery > Configuration > Edit the Identity source for the Domain.
3. Change your Primary Server URL for your domain from secure LDAP to Standard by changing the URL and port number.
Before:
Secure Global Catalog address: ldaps://<global_server>:3269
After:
Global Catalog address: ldap://<global_server>:3268
regards