获取mailchimp的列表

I am using MailChimp api, and I want to get Mailchimp Lists. This is my php code to get the lists, which worked perfectly, but now it returns an empty result.

    $ch = curl_init('http://'.$value -> responce -> dc.'.api.mailchimp.com/3.0/lists?apikey='.$access_key);

    curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); 

    $res = curl_exec($ch);

Does anyone know why?