problem in query_vars parameters

Hi,
I’ve a problem. I’ve tried a lot of things but I could not find a solution.
I use query_vars parameters in this page and there isn’t any problem. But i don’t use different parameters or the same parameters in different custom page. Parameter value is always empty.
Parameters used once ?
Function.php :

function parameter($qvars)
{
$qvars[] = 'kategori';
$qvars[] = 'ara';
$qvars[] = 'numara';
$qvars[] = 'tur';
return $qvars;
}
add_filter('query_vars', 'parameter');

videolar.php (../videolar?tur=test) :

global $wp_query;
echo $wp_query->query_vars['tur'] // empty

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