Which registry keys to force password protection of s/mime key ?

For S/MIME implementation in Outlook 2010 / Windows 7, I want the users private key protected with password (high security : password required for each encrypting / decoding action).

I have set these registry keys (found in an old post) :

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Cryptography

<new DWORD Value "PrivKeyCacheMaxItems"=dword:00000000>

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Cryptography

<new KEY "Protect" ; new DWORD Value "AllowCachePW"=dword:00000000>

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Cryptography

<new DWORD Value "ForceKeyProtection"=dword:2>

It doesn't work ;-)
Thanks for any help.