authentication with coldfusion

If I use the default config.cfm and change false to true then ckfinder works fine. Next I want to authenticate so I am writing a session var called IsAuthenticated (to true) and I can see this is being done. Then in config.cfm I have

function CheckAuthentication()
{
if ( structKeyExists(session, "IsAuthenticated") and session.IsAuthenticated )
{
return true;
}
return false;
}

But when I try and use CKfinder I see "The file browser is disabled for security reasons. Please contact your system administrator and check the CKFinder configuration file"

Any idea what the issue is?

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