php - Google Analytics API: Finding user age bracket and gender information -

i'm trying find age bracket , gender information of users using google analytics api using php. query tried running:

function user_gender(&$analytics, $profileid) {    $optparams = array(     'dimensions' => 'ga:usergender',     );    return $analytics->data_ga->get(       'ga:' . $profileid,       '30daysago',       'today',       'ga:users',       $optparams         ); } 

however, above query doesn't return anything. have used users metric along usergender dimension. seems wrong query?