The rule looks like it might not be correct, in my pages it looks like this:
if (!WA_Auth_RulePasses("Logged in to users")){
WA_Auth_RestrictAccess("users_LogIn.php");
}
Did you make sure that you have the WA_SecurityAssist folder uploaded to the site? You may be experiencing a problem with the version of the helper file that you have.
If you continue to have this problem look in your WA_SecurityAssist folder for the helper file. Make a backup of this page, then use the attached version of this page in it's place.