如何在SOCKS 5中使用CURL PHP

I have find socks and check a socks live, and code below :

$url = 'http://example.com';
$ch = curl_init (); 
curl_setopt ($ch, CURLOPT_URL, $url); 
curl_setopt ($ch, CURLOPT_PROXY, "76.8.6.203:37639"); 
//curl_setopt ($ch, CURLOPT_PROXYTYPE, CURLPROXY_SOCKS5); 
curl_setopt ($ch, CURLOPT_PROXYTYPE, 7);
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, TRUE); 
curl_setopt ($ch, CURLOPT_FAILONERROR, true); 
curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1); 
$data = curl_exec($ch); 
curl_close ($ch); 

echo $data;

Although i use CURLOPT_PROXYTYPE is 7 or CURLPROXY_SOCKS5 then error 502! Thanks please help me!