Installed VSC 6.0 on Windows Server 2008 R2 then registered its IP  to VCSA6.0U2 (vcenter server appliance) successfully.
 
Added NetApp manually in VCSA successfully.
 
NetApp storage info / data became visible in NetApp VSC.
 
After few min,
 
VSC 6 Plug-in unregistered by itself and VSC 6 Plug-in dropped from INSTALLED PLUG-IN (upper section) to AVAILABLE PLUG-IN (lower section)
 
When I checked the VSC6 registration html page (still left open from last registration attempt) ) in WinSerevr 2008, the PASSWORD field showed blank (it was *********** before)
 
As soon as I retyped the VCSA's root password,  VSC plug-in in VCSA was restored.
 
Any advise ?
 
Thanks !!!