try this workaround if the issue still exists. more details are available in the following community thread.
http://communities.vmware.com/thread/425351?start=0&tstart=0
Start the installation with a local admin on the VC machine, using the parameter as below.
VMware-vsamanager-en-5.1.0-825249.exe /v"VM_SHOWNOAUTH=1"
During the installation wizard, you will be prompted to enter username and password credentials.
Authenticate against VC using any account that has administrative permissions against VC,
this can be a SSO local account (for example vsaadmin@system-domain) or even a ldap account.