无法以编程方式反序列化SOAP消息

当我尝试反序列化soap消息时，我得到以下异常。我这样做是因为我有想要在测试中重用的响应文件。我不能使用真正的服务或类似的东西，因为它不适合我们现有的测试框架的架构。

    Test 'MyUnitTestMethod' failed: System.InvalidOperationException : There is an error in XML document (1, 2).
----> System.InvalidOperationException : <MySpecialResponse xmlns='http://xsd.com/msgs/v1'> was not expected. 
at System.Xml.Serialization.XmlSerializer.Deserialize(XmlReader xmlReader, String encodingStyle, XmlDeserializationEvents events) 
at System.Xml.Serialization.XmlSerializer.Deserialize(XmlReader xmlReader, String encodingStyle) 
at System.Xml.Serialization.XmlSerializer.Deserialize(Stream stream)

private const string _content =
@"<soapenv:Envelope xmlns:soapenv=""http://schemas.xmlsoap.org/soap/envelope/"">
  <soapenv:Body>
    <ns3:MySpecialResponse xmlns:ns3=""http://xsd.com/msgs/v1"" >
      <header>
        <status>0</status>
      </header>
      <ns3:Payload>
        <ns3:CustomerName>name</ns3:CustomerName>
        <ns3:EmailAddress>test1@mail.com</ns3:EmailAddress>
      </ns3:Payload>
    </ns3:MySpecialResponse>
  </soapenv:Body>
</soapenv:Envelope>";
/// <remarks/>
[System.CodeDom.Compiler.GeneratedCodeAttribute("System.Xml", "2.0.50727.3082")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true, Namespace="http://xsd.com/msgs/v1")]
public partial class MySpecialResponse : BaseResponse {
    private MySpecialPayload payloadField;
    /// <remarks/>
    public MySpecialPayload Payload {
        get {
            return this.payloadField;
        }
        set {
            this.payloadField;= value;
        }
    }
}
[System.CodeDom.Compiler.GeneratedCodeAttribute("System.Xml", "2.0.50727.3082")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType=true, Namespace="http://xsd.com/msgs/v1")]
public partial class MySpecialPayload {
    private string customerNameField;
    private string emailAddressField;
    /// <remarks/>
    public string CustomerName {
        get {
            return this.customerNameField;
        }
        set {
            this.customerNameField = value;
        }
    }
    /// <remarks/>
    public string EmailAddress {
        get {
            return this.emailAddressField;
        }
        set {
            this.emailAddressField = value;
        }
    } 
}
//The code I am using - might not be right?
  var serialiser = new System.Xml.Serialization.XmlSerializer(typeof(MySpecialResponse));

  using (var stream = new MemoryStream(Encoding.ASCII.GetBytes(_content))
  { 
      var doc = new System.Xml.XmlDocument();
      doc.Load(stream);
      var nsManager = new System.Xml.XmlNamespaceManager(doc.NameTable);
      nsManager.AddNamespace("soapenv", "http://schemas.xmlsoap.org/soap/envelope/");
      //so I can get the actual response and not the soap body
      var node = doc.SelectSingleNode("//soapenv:Body", nsManager);
      if (node != null)
      {
           byte[] xml = Encoding.UTF8.GetBytes(node.InnerXml);
           using (var memStream = new System.IO.MemoryStream(xml))
           {
                memStream.Position = 0;
                var resp = (MySpecialResponse)serialiser.Deserialize(memStream);  //Throws exception here
            }
      }
  }

（BaseResponse有标题字段）

任何关于异常的想法都会被提出，以及我如何获得soap消息来将消息反序列化到对象中，无论是修复我的代码还是应用其他技术。

注意：我有很多文件想要使用一种通用方法进行反序列化，所以我不会提前知道所有的xml名称空间，只知道根响应类型。

感谢