Handling custom datacontract serialization at WCF endpoint breakpoint

I want to use XML attributes instead of elements in xmlrequest and xmlresponse, I have implemented IXmlSerializable like this:

public partial class Id : IXmlSerializable
{

    /// <remarks/>
    [XmlAttribute]
    public string lmsId;

    /// <remarks/>

    [XmlAttribute]
    public string unitId;

    /// <remarks/>

    [XmlAttribute]
    public string lmsPresId;

    /// <remarks/>

    [XmlAttribute]
    public string callId;

    public System.Xml.Schema.XmlSchema GetSchema()
    {
        return null;
    }

    public void ReadXml(System.Xml.XmlReader reader)
    {
        //implement if remote callers are going to pass your object in
    }

    public void WriteXml(System.Xml.XmlWriter writer)
    {
        writer.WriteAttributeString("lmsId", lmsId.ToString());
        writer.WriteAttributeString("unitId", unitId.ToString());
        writer.WriteAttributeString("lmsPresId", lmsPresId.ToString());
        writer.WriteAttributeString("callId", callId.ToString());
    }
}

      

        
        
        
      

    

But my service help shows request and response as unknown

I have tried even XmlSerializerFormat

[System.ServiceModel.MessageContract]
public partial class Id
{

    /// <remarks/>
    [XmlAttribute, MessageBodyMember]
    public string lmsId;

    /// <remarks/>

    [XmlAttribute, MessageBodyMember]
    public string unitId;

    /// <remarks/>

    [XmlAttribute, MessageBodyMember]
    public string lmsPresId;

    /// <remarks/>

    [XmlAttribute, MessageBodyMember]
    public string callId;
}

      

        
        
        
      

    

then i get everything in xml as xmlElements instead of XmlAttributes. But I am getting all data as elements instead of Xmlattributes.