Cannot enable Identity Guard in Google Chrome

Norton Password Manager
1

I Cannot enable Norton Identity Safe (Identity Guard v 21.1.0.18) in Google Chrome, Version 33.0.1750.117 beta-m.

 

Identity Guard appeas in the Chrome extensions window (Settings, Extension).  However, the feature cannot be enabled.

 

"Enable extensions" is active in Internet Options (accessible from Control Panel).

 

Both Identity Guard and Google Chrome are up to date.

 

OS = Windows Vista 64 bit