Build: 13.1.20131.2107

In my webdatagrid, I programmatically populate all the columns. I had multiline texteditorprovider for all text fields. Now I had a problem after I add the sorting behaviour. Whenever, I sort a column, it is working the first time. However, it is broken the second time. It generate the following exception.

Exception type: NullReferenceException
Exception message: Object reference not set to an instance of an object.
at Infragistics.Web.UI.GridControls.Sorting.AddHeaderImgToCaption(GridField column, SortDirection direction)
at Infragistics.Web.UI.GridControls.Sorting.BehaviorEvents_PreRender(Object sender)
at Infragistics.Web.UI.GridControls.GridBehaviorEvents.RenderingContentHandler.Invoke(Object sender)
at Infragistics.Web.UI.GridControls.GridRenderer.RenderContents(HtmlTextWriter writer)
at Infragistics.Web.UI.Framework.RunBot.HandleRenderContents(HtmlTextWriter writer, RendererBase renderer)
at Infragistics.Web.UI.GridControls.WebDataGrid.GetRenderHTML()
at Infragistics.Web.UI.GridControls.WebDataGrid.CallbackRender(CallbackObject callbackObject)
at Infragistics.Web.UI.Framework.RunBot.CallbackRenderRecursive(CallbackObject callbackObject)
at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
at System.Web.UI.HtmlControls.HtmlForm.RenderChildren(HtmlTextWriter writer)
at System.Web.UI.HtmlControls.HtmlContainerControl.Render(HtmlTextWriter writer)
at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter)
at Infragistics.Web.UI.Framework.RunBot.RenderPageCallBack(HtmlTextWriter writer, Control control)
at System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children)
at System.Web.UI.Page.Render(HtmlTextWriter writer)
at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter)
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

<The following code is used to generate the columns>

private void CreateColumns(DataTable theWholeTable, string tableName, int columnWidth)
        {
            //create editing core behaviour
            TableDetailGrid.Behaviors.CreateBehavior<Activation>();
            TableDetailGrid.Behaviors.CreateBehavior<EditingCore>();
            TableDetailGrid.Behaviors.EditingCore.AutoCRUD = false;
            TableDetailGrid.Behaviors.EditingCore.BatchUpdating = true;
            TableDetailGrid.Behaviors.EditingCore.Enabled = true;
            TableDetailGrid.Behaviors.EditingCore.Behaviors.CreateBehavior<CellEditing>();
 
            //create an editor provider
            var textprovider = new TextEditorProvider(ID = "MultilineTextProvider");
            textprovider.EditorControl.TextMode = TextBoxMode.MultiLine;
            TableDetailGrid.EditorProviders.Add(textprovider);
 
            //create RowAdding behaviour
            TableDetailGrid.Behaviors.EditingCore.Behaviors.Add(
            TableDetailGrid.Behaviors.EditingCore.Behaviors.CreateBehavior<RowAdding>());
            TableDetailGrid.Behaviors.EditingCore.Behaviors.RowAdding.EditModeActions.EnableOnActive = true;
            TableDetailGrid.Behaviors.EditingCore.Behaviors.RowAdding.EditModeActions.MouseClick = EditMouseClickAction.Single;
            TableDetailGrid.Behaviors.EditingCore.Behaviors.RowAdding.Enabled = true;
            TableDetailGrid.Behaviors.EditingCore.Behaviors.RowAdding.Alignment = AddNewRowAlignment.Top;
            TableDetailGrid.Behaviors.EditingCore.Behaviors.RowAdding.AddNewRowClientEvents.EnteringEditMode = "AddRow_EnteringEditMode_CancelEventIfReadOnly";
            
            //create RowDeleting behaviour
            TableDetailGrid.Behaviors.EditingCore.Behaviors.Add(
                TableDetailGrid.Behaviors.EditingCore.Behaviors.CreateBehavior<RowDeleting>());
            TableDetailGrid.Behaviors.EditingCore.Behaviors.RowDeleting.Enabled = true;
 
            //get readonly column names
            var readOnlyColumnNames = GetReadOnlyColumnNamesByTable(tableName);
 
            //create sorting behaviour
            var sortingBehaviour = TableDetailGrid.Behaviors.CreateBehavior<Sorting>();
            sortingBehaviour.SortingMode = SortingMode.Multi;
 
            foreach (DataColumn column in theWholeTable.Columns)
            {
                var theColumn = new BoundDataField(true);
                theColumn.Key = column.ColumnName;
                theColumn.Header.Text = column.Caption;
                theColumn.DataFieldName = column.ColumnName;
                theColumn.DataType = "System.String";
                theColumn.Width = columnWidth;
                TableDetailGrid.Columns.Add(theColumn);
 
                //create column settings
                var settingColumn = new EditingColumnSetting();
                
                settingColumn.ColumnKey = column.ColumnName;
                settingColumn.ReadOnly =
                    (readOnlyColumnNames.Contains(column.ColumnName, StringComparer.InvariantCultureIgnoreCase) ||
                     string.Equals(column.ColumnName, Session["PrimaryKeyName"].ToString(), StringComparison.InvariantCultureIgnoreCase));
                if (string.Equals(tableName, "dbo.CustomColumn", StringComparison.InvariantCultureIgnoreCase) &&
                    string.Equals(column.ColumnName, "SourceColumn", StringComparison.InvariantCultureIgnoreCase))
                {
                    settingColumn.EditorID = textprovider.ID;
                }
 
                ////create sorting column settings
                sortingBehaviour.SortedColumns.Add(TableDetailGrid.Columns[column.ColumnName], Infragistics.Web.UI.SortDirection.Ascending);
 
                TableDetailGrid.Behaviors.EditingCore.Behaviors.CellEditing.ColumnSettings.Add(settingColumn);
            }
        }

<This is the configuration of the webdatagrid in the aspx>

<ig:WebDataGrid ID="TableDetailGrid" runat="server" ClientIDMode="Static" Height="100%" Width="100%" EnableAjax="False" 
				OnRowAdding="TableDetailGridRowAdding" OnRowUpdating="TableDetailGridRowUpdating" OnRowsDeleting="TableDetailGridRowDeleting">
				<AjaxIndicator Location="MiddleCenter" />
					<Behaviors>
					   <%-- <ig:Paging PagerAppearance="Bottom" PageSize="10" Enabled="true" />--%>
						<ig:Filtering Alignment="Top" Visibility="Visible" Enabled="true" FilterType="ExcelStyleFilter">
						</ig:Filtering>
						<ig:ColumnResizing Enabled="true">
							<ColumnSettings>
								<ig:ColumnResizeSetting EnableResize="true" />
							</ColumnSettings>
						</ig:ColumnResizing>
						<ig:Activation Enabled="True"/>
						<ig:Selection RowSelectType="Multiple" Enabled="true" ColumnSelectType="Single" CellClickAction="row" />
						<ig:RowSelectors RowNumbering="true" Enabled="true" />
						<ig:VirtualScrolling ScrollingMode="Virtual" DataFetchDelay="500" RowCacheFactor="3" ThresholdFactor="0.5" Enabled="true" />
					</Behaviors>
					<EmptyRowsTemplate>
						<div id="divAttention" style="text-align: left;">
							<br />
							<img alt="Attention" src="/Images/attention.png" />
						</div>
					</EmptyRowsTemplate>
					<ErrorTemplate>
						<div style="text-align: left">
							<br />
							<img alt="Error" src="/Images/error.png" />
							<%= GetGlobalResourceObject("DataManager_English","ErrorTemplateMessage") %>
					</ErrorTemplate>
			</ig:WebDataGrid>

Can someone please help let me know why the textprovider does not work with the Sorting behaviour? Thank you so much.