Auth_HTTP setIdle() and setExpire()

I see that Auth_HTTP inherits setIdle() and setExpire() from Auth::DB but I can't seem to get the Authentication to expire for me. Here is a sample of what I am trying. Any thoughts? Does anyone know of any other examples of Auth_HTTP that I can look at besides what is in the pear docs? Thanks require_once("Auth/HTTP.php"); $AuthOptions = array( 'dsn'=>"mysql://user:pass@localhost/auth", 'table'=>"tbl_auth", 'usernamecol'=>"username", 'passwordcol'=>"password", 'cryptType'=>"md5", 'dbFields'=>"*" ); $a = new Auth_HTTP("DB", $AuthOptions); $a->setRealm('yourrealm'); $a->setIdle(30, true); $a->setExpire(30); $a->start(); $a->setCancelText('<h2>Error 401</h2>'); if($a->getAuth()) {

    echo "Hello $a->username welcome to my secret page <BR>";
    echo "Your details on file are: <BR>";
    echo $a->getAuthData('userid');        // retriving other details from the database row
    echo $a->getAuthData('telephone');      // in this example the user id, telephone number
    echo $a->getAuthData('email');        // and email address

};