C# 向带有AddressHeader.CreateAddressHeader的标头添加标记

我正在尝试向SOAP请求的标头添加一些标记，但无法插入此标记：

    <ReplyTo xmlns="http://www.w3.org/2005/08/addressing">
        <Address>http://www.w3.org/2005/08/addressing/anonymous</Address>
    </ReplyTo>

http://www.w3.org/2005/08/addressing/anonymous

我试着这样插入它：

   string cValue = "<Address>http://www.w3.org/2005/08/addressing/anonymous</Address>";
   AddressHeader oReplyTo = AddressHeader.CreateAddressHeader("ReplyTo",
                                                              "http://www.w3.org/2005/08/addressing",
                                                              cValue);

string cValue=”http://www.w3.org/2005/08/addressing/anonymous";
AddressHeader oReplyTo=AddressHeader.CreateAddressHeader（“ReplyTo”，
"http://www.w3.org/2005/08/addressing",
价值）；

但我得到了这个结果：

<ReplyTo xmlns="http://www.w3.org/2005/08/addressing">&lt;Address&gt;http://www.w3.org/2005/08/addressing/anonymous&lt;/Address&gt;</ReplyTo>

Addresshttp://www.w3.org/2005/08/addressing/anonymous/Address

我怎样才能正确地做呢？除了AddressHeader.CreateAddressHeader，还有其他方法吗