set up rest with https

I have set up REST server support https using my own generated certificate.

Then I have the client POSTing data using https. But it seems not work. When using http it works. Here the code

PHP Code:

case "POST": // Used to create a new object on the server (INSERT)
    if($data === NULL){
        return FALSE;
    } else {
       $fields_string = "";
       foreach($data as $key=>$value){
            $fields_string .= $key.'='.$value.'&';
       }
       $fields_string = rtrim($fields_string,'&');
       $ch = curl_init($url);
       curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
       curl_setopt($ch,CURLOPT_POST,count($data));
       curl_setopt($ch,CURLOPT_POSTFIELDS,$fields_string);
       if($scheme == 'https'){
            curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, TRUE);
            curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
            $cert = config_item('cert_path');
            curl_setopt($ch, CURLOPT_CAINFO, $cert);
       }
       $rdata = curl_exec($ch);
       $this->responseCode = curl_getinfo($ch,CURLINFO_RESPONSE_CODE);
       curl_close($ch);
   }
   break; 


I'm sure config_item('cert_path') points to certificate file downloaded from server

Tell me if I'm wrong setting up curl.
Also, how to know if my clients certificate rejected by server? Is CI reports it in log (server) or log (client)?