I have installed a second vCenter using simple installation and found that I can't use link mode due to SSO.
So I followed the instruction to remove and reinstall the second vcenter according to this KB: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2036722
However, I am not able to remove and reinstall the web client as it keep prompting "fields cannot be left blank." despite there are only 2 fields and both fields are filled.
I also tried to re-register the web client with the first vCenter Single Sign-On instance according to this KB: http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&docType=kc&docTypeID=DT_KB_1_1&externalId=2033620#Register
However, I am not able to register as it prompt "The system cannot find the path specified. Error connecting to VMware Lookup Service https://vcenterhq.cg.local:7444/lookup/service/sdk"