The following class works with a memory database, but when I do a build against a postgres database I get the following error: Literal type 'NNet.Model.Common.Web.HTMLLink+ContentType' is not supported. If I remove the ContentType default, then I get the same message for LocationType.

   [HierarchyRoot(InheritanceSchema = InheritanceSchema.SingleTable)]
    public class HTMLLink : NNetEntity {

        /// <summary> Type of page at end of link </summary>
        public enum ContentType {
            /// <summary> link to a review page (mainly for services) </summary>
            Review,
            /// <summary> link to an information page</summary>
            Information,    // link to an information page
            /// <summary> link to an article</summary>
            Article,
            /// <summary> link to an Award</summary>
            Award,
        };

        /// <summary> Location of page </summary>
        public enum LocationType {
            Internal,       // Link to an internal neighbournet page, used until ages imported
            External        // Link to external page
        };

        [Field]
        public string URL { get; set; }
        [Field]
        public DateTime Published { get; set; }
        /// <summary> Type of page at end of link </summary>
        [Field(DefaultValue = ContentType.Article)]
        public ContentType Content { get; set; }
        /// <summary> Location of page </summary>
        [Field(DefaultValue = LocationType.Internal)]
        public LocationType Location { get; set; }

        public HTMLLink() { }

    }