Enum as Key in RIA Services

In my entity class i use enum as a key property:

[DataContract]
public class MultimediaType
{
    [DataMember]
    [Key]
    public Identificator Id { get; set; }
    [DataMember]
    public string Name { get; set; }
    [DataMember]
    public string Description { get; set; }

    [DataContract]
    public enum Identificator
    {
        [EnumMember]
        Image = 1,
        [EnumMember]
        Video = 2,
        [EnumMember]
        Sound =开发者_StackOverflow中文版 3
    }
}


[EnableClientAccess()]
public class DomService : DomainService
{
    List<MultimediaType> _multimediaTypes = new List<MultimediaType>()
    {
        new MultimediaType()
        {
            Id = MultimediaType.Identificator.Image,
            Name = "Image",
            Description = "This is type for all images."
        },
        new MultimediaType()
        {
            Id = MultimediaType.Identificator.Video,
            Name = "Video",
            Description = "This is type for all videos."
        },
        new MultimediaType()
        {
            Id = MultimediaType.Identificator.Sound,
            Name = "Sound",
            Description = "This is type for all sounds."
        },
    };

    [Query]
    public IQueryable<MultimediaType> GetMultimediaTypes()
    {
        return _multimediaTypes.AsQueryable();
    }
}

My client is SilverLight application that consume my domain service.

I have no idea what is wrong, but i obtaint this error:

The property 'MultimediaType.Id' is marked as a key property, but it's not serializable. Are you missing DataMemberAttribute?

Do you have any idea what i do wrong? Thanks a lot!

EnumMemberAttribute : Specifies that the field is an enumeration member and should be serialized.

Check the below lins :

http://msdn.microsoft.com/en-us/library/system.runtime.serialization.enummemberattribute(v=vs.95).aspx

Sharing Enum with WCF Service

Also take a look at the Remarks and Example