I am trying to add Session State to my app. I want to store session in SQL. One item that is being saved to session is the webdatagrid sorting information.  When I attempt to serialize my object right before sending it to session I get this error:

Type 'Infragistics.Web.UI.GridControls.SortedColumnInfoCollection' in Assembly 'Infragistics4.Web.v13.1, Version=13.1.20131.1012, Culture=neutral, PublicKeyToken=7dd5c3163f2cd0cb' is not marked as serializable.

I am trying to save the SortedColumnInfoCollection to session so I can reset the grid when the user returns to it. There is no inner exception. The object that I store this information is marked a Serializalbe and it inherts ISerializable. If I take out the SortedColumnInfoCollection, it works. But I want to save that information or I will have to remove that feature from the users.  And I would rather not do that.  Does anyone know how to get around this?

Here is a copy of the Object that I am trying to Serialize.

    [Serializable]
    public class GridSettingsHolder : ISerializable
    {
        protected SortedColumnInfoCollection _columnSortInfo;
        protected ColumnFilters _columnFilters;

        public GridSettingsHolder()
        {           
        }

        public Infragistics.Web.UI.GridControls.SortedColumnInfoCollection ColumnSortingInfo
        {
            get { return _columnSortInfo; }
            set { _columnSortInfo = value; }
        }

        public Infragistics.Web.UI.GridControls.ColumnFilters ColumnFilters
        {
            get { return _columnFilters; }
            set { _columnFilters = value; }
        }

        public void GetObjectData(SerializationInfo info, StreamingContext context)
        {           
           info.AddValue("ColumnSortingInfo", this._columnSortInfo);
            info.AddValue("ColumnFilters", this._columnFilters);           
        }

        public GridSettingsHolder(SerializationInfo info, StreamingContext ctxt)
        {

            this._columnSortInfo = (SortedColumnInfoCollection)info.GetValue("ColumnSortingInfo", typeof(SortedColumnInfoCollection));
            this._columnFilters = (ColumnFilters)info.GetValue("ColumnFilters", typeof(ColumnFilters));                       
        }       
    }