php发送企业消息一直失败求救啊！！不同写法。

$ACCESS_TOKEN=$_COOKIE['cookie_AccessToken'];
    $url  = "https://oapi.dingtalk.com/message/send?access_token=$ACCESS_TOKEN";  
    $post_data = array(
        'touser'  => '01502353615121',
        'agentid' => '14269822',
        'msgtype' => 'text',
                'text'=>array('content'=>'8888')
        );
    
    $post_data=json_encode($post_data);
    echo "post_data:$post_data";echo "<BR>";
    
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_HTTPHEADER,array('Content-Type: application/json; charset=utf-8'));


    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);


    $output = curl_exec($ch);
    curl_close($ch);


一直发送不成功，没有任何的返回信息。
请高手帮忙处理。。