Registry edit "access denied" help?

[quickdraw62]

Does anyone know why when I try to add a registry key I get an error "access denied"?

I'm trying to add a key, then a DWORD for changing the text color of the dialpad numbers (ones that show up as you enter the phone number) and am getting the error trying to add a new registry key.

The hack I'm trying to do is in HKLM\Security\Dialer\phone\skin\landscape and also one in portrait.

I'm guessing the the security reg key is what is not allowing me to edit this but is there a way to take control of it to make my modifications?