404错误的请求Streamsend API C#

我正在尝试添加新的所有者，使用c#代码连接到streamsend api。我根据文档发送xml：http://app.streamsend.com/docs/api/OwnersController.html

这是xml。

strbuild.Append("<owner>");
strbuild.AppendLine("<owner-id>" + strOwnerID + " </owner-id>");
strbuild.AppendLine("<owner-name>" + strOwnerName + "</owner-name>");
strbuild.AppendLine("<from-name>" + strFromName + "</from-name>");
strbuild.AppendLine("<from-email-address>" + strEmailAddress + "</from-email-      address>");
strbuild.AppendLine("<from-street-address-1>" + strStreetAddress + "</from-street- address-         1>");
strbuild.AppendLine("<from-street-address-2>" + "XXXYYY" + "</from-street-address-2>");
strbuild.AppendLine("<from-city>" + strFromCity + "</from-city>");
//strbuild.AppendLine("<from-state>" + "VIRGINIA" + "</from-state>");
strbuild.AppendLine("<from-zip>" + strFromZip + "</from-zip>");
strbuild.AppendLine("<from-country>" + strFromCountry + "</from-country");
strbuild.AppendLine("</owner>");

远程服务器返回错误：(400) bad request

可能出了什么问题。请回复。