WCF操作契约在应该返回List时返回void

我的问题是在操作合同，当我在客户端消费WCF服务，并尝试使用方法/操作合同，我没有得到相同的方法名称;也就是说，我得到"MethodNameAsync"与void返回，它应该返回一个列表/单个对象(s)..

编辑:

我的客户端/消费者是一个silverlight应用程序

这是我的WCF的代码示例

[ServiceContract]
public interface ICRUDManagerService
{
    [OperationContract]
    List<MyCustomObject> GetAllCustomObjects();
}

---

public class CRUDManagerService : ICRUDManagerService
{
    public List<MyCustomObject> GetAllCustomObjects()
    {
        return MyCustomObject.GetAllCustomObjects();
    }
}

---

[DataContract]
public class MyCustomObject:INotifyPropertyChanged
{
    #region [ Public Properties and their Private Fields ]
    private Int32 _iSerial;
    [DataMember]
    public Int32 iSerial
    {
        get
        {
            return this._iSerial;
        }
        set
        {
            if (value != this._iSerial)
            {
                this._iSerial = value;
                RaisePropertyChanged("iSerial");
            }
        }
    }
    private string _code;
    [DataMember]
    public String Code
    {
        get
        {
            return this._code;
        }
        set
        {
            if (value != this._code)
            {
                this._code = value;
                RaisePropertyChanged("Code");
            }
        }
    }
    private string _ename;
    [DataMember]
    public String Ename 
    {
        get
        {
            return this._ename;
        }
        set
        {
            if (value != this._ename)
            {
                this._ename = value;
                RaisePropertyChanged("Ename");
            }
        }
    }
    private string _aname;
    [DataMember]
    public String Aname
    {
        get
        {
            return this._aname;
        }
        set
        {
            if (value != this._aname)
            {
                this._aname = value;
                RaisePropertyChanged("Aname");
            }
        }
    }
    private Int32? _defaultRoutID;
    [DataMember]
    public Int32? DefaultRoutID 
    {
        get
        {
            return this._defaultRoutID;
        }
        set 
        {
            if (value != this._defaultRoutID)
            {
                this._defaultRoutID = value;
                RaisePropertyChanged("DefaultRoutID");
            }
        }
    }
    #endregion [ End of Public Properties ]
    #region Implement INotifyPropertyChanged
    public event PropertyChangedEventHandler PropertyChanged;
    public void RaisePropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
    }
    #endregion
    public static MyCustomObject GetDTOFromDALObject(CustomeEntites.Model.MyEntityObject src)
    {
        MyCustomObject  obj = new MyCustomObject();
        obj.iSerial = src.iSerial;
        obj.Code = src.Code;
        obj.Ename = src.Ename;
        obj.Aname = src.Aname;
        obj.DefaultRoutID = src.DefaultRoutID;
        return obj;
    }
    public CustomeEntites.Model.MyEntityObject GetDALObject()
    {
        CustomeEntites.Model.MyEntityObject obj = new CustomeEntites.Model.MyEntityObject();
        obj.iSerial = iSerial;
        obj.Code = Code;
        obj.Ename = Ename;
        obj.Aname = Aname;
        obj.DefaultRoutID = DefaultRoutID;
        return obj;
    }
    static public List<MyCustomObject> GetAllCustomObjects()
    {
        using (CustomeDBEntites context = new CustomeDBEntites ())
        {
            List<WF_MyCustomObject> _ReturnableList = new List<WF_MyCustomObject>();
            foreach (MyEntityObject item in context.MyEntityObject.ToList())
            {
                _ReturnableList.Add(GetDTOFromDALObject(item, false));
            }
            return _ReturnableList;
        }
    }
}