You probabaly just need to re-register the plugin, try this:
1. Start by closing the vsphere client.
2. Log in to the vShield Manager web user interface
3. Go to Setting & Reports -> click on Unregister the vShield Plug-in. If it says it's not registered, then register and unregister.
4. Now register the plug-in. If it says it has not been registered (the button will say Register) then click on register, then unregister and register again.
5. Launch the vsphere client and verify.
If this does not work you can try disabling the existing plug-in first
a. From the vsphere client go to Plug-ins --> Manager Plug-ins
b. Right-click the "vShield Manager" plug-in and select Disable.
c. Repeat steps 1 - 5 listed above