PHP在执行curl时将连字符转换为三个点

我正在尝试使用Curl从PHP调用。net web服务。每次我尝试这样做，我得到一个错误的编码。上面说，如果……不支持8。当我检查tcpdump (PacketPeeper)时，我看到由于某种原因curl将字符串"utf-8"转换为"utf…8"。实际上，它将所有的"-"转换为"…"。

知道为什么吗?

$req = "<?xml version='"1.0'" encoding='"utf‐8'"?>
    <soap:Envelope xmlns:xsi='"http://www.w3.org/2001/XMLSchema‐instance'"
    xmlns:xsd='"http://www.w3.org/2001/XMLSchema'"
    xmlns:soap='"http://schemas.xmlsoap.org/soap/envelope/'">
    <soap:Body>
        <GenerateLink>
        ..............  
        </GenerateLink>
        </soap:Body>
    </soap:Envelope>";
$soap_do = curl_init(); 
curl_setopt($soap_do, CURLOPT_URL,            "http://www.myurl.com/serv.asmx" );   
curl_setopt($soap_do, CURLOPT_FOLLOWLOCATION, true); 
curl_setopt($soap_do, CURLOPT_RETURNTRANSFER, true );
curl_setopt($soap_do, CURLOPT_POST,           true ); 
curl_setopt($soap_do, CURLOPT_POSTFIELDS,     $req); 
curl_setopt($soap_do, CURLOPT_HTTPHEADER,     array('Content-Type: text/xml; charset: utf-8' ,'SOAPAction: "http://www.myurl.com/serv.asmx"', 'Content-Length: '.strlen($req) )); 

$response = curl_exec($soap_do);