WCF MessageContract属性未显示在WSDL中

Question

MessageContract为了Stream通过WCF与其他一些数据一起传输，我定义了一个：[MessageContract]public class DTSetGeotagImageMessage{    [MessageHeader(MustUnderstand = true)]    public DTGeotagImageFileInfo GeotagImageFileInfo;    [MessageBodyMember(Order = 1)]    public Stream FileData;}public class DTGeotagImageFileInfo{ //All these properties are not showing up in the WSDL:    public long? GeotagID { get; internal set; }    public string GeotagGuid { get; internal set; }    public string ImageGuid { get; internal set; }    public long GeotagFieldId { get; internal set; }    public double Lat { get; internal set; }    public double Lon { get; internal set; }}WSDL：<xs:complexType name="DTGeotagImageFileInfo"> <xs:sequence/></xs:complexType><xs:element name="DTGeotagImageFileInfo" nillable="true" type="tns:DTGeotagImageFileInfo"/>但是标头数据类的属性未显示在WSDL文件中。如何让他们出现？