Hi,

I am getting this error, but I can't why what I did wrong.  Does anyone know what this mean? Thanks you.

Message: System.ArgumentNullException: Value cannot be null.
Parameter name: containingFormulaRef
   at Infragistics.Win.UltraWinGrid.FormulaTargetRefBase..ctor(UltraGridLayout layout, FormulaRefBase containingFormulaRef, Object context)
   at Infragistics.Win.UltraWinGrid.SummaryValue.get_CalcReference()
   at Infragistics.Win.UltraWinGrid.UltraGridRow.CopyFormulaSummaryValues(RowsCollection source, RowsCollection dest)
   at Infragistics.Win.UltraWinGrid.UltraGridRow.CopyRowPropertiesFrom(UltraGridRow source, RowPropertyCategories rowProperties)
   at Infragistics.Win.UltraWinGrid.UltraGrid.CopyPropertiesToPrintRow(UltraGridRow printRow)
   at Infragistics.Win.UltraWinGrid.UltraGrid.FireInitializeGroupRow(InitializeGroupByRowEventArgs e)
   at Infragistics.Win.UltraWinGrid.UltraGridGroupByRow.FireInitializeRow()
   at Infragistics.Win.UltraWinGrid.RowsCollection.CreateGroupByRowsHelper(UltraGridRow[ rows, Int32& startIndex, Boolean rowsAlreadySorted)
   at Infragistics.Win.UltraWinGrid.RowsCollection.InitGroupByRows()
   at Infragistics.Win.UltraWinGrid.RowsCollection.SyncRowsHelper(IList boundList)
   at Infragistics.Win.UltraWinGrid.RowsCollection.SyncRows()
   at Infragistics.Win.UltraWinGrid.RowsCollection.EnsureNotDirty()
   at Infragistics.Win.UltraWinGrid.RowsCollection.EnsureFiltersEvaluated()
   at Infragistics.Win.UltraWinGrid.ScrollCountManagerSparseArray.VerifyAgainstScrollVersion()
   at Infragistics.Win.UltraWinGrid.RowsCollection.get_ScrollCount()
   at Infragistics.Win.UltraWinGrid.UltraGridLayout.get_RowScrollRange()
   at Infragistics.Win.UltraWinGrid.RowScrollRegion.GetMaxScrollPosition(Boolean scrollToFill)
   at Infragistics.Win.UltraWinGrid.RowScrollRegion.EnsureScrollRegionFilled(Boolean calledFromRegenerateVisibleRows)
   at Infragistics.Win.UltraWinGrid.RowScrollRegion.RegenerateVisibleRows(Boolean resetScrollInfo)
   at Infragistics.Win.UltraWinGrid.RowScrollRegion.WillScrollbarBeShown(ScrollbarVisibility assumeColScrollbarsVisible)
   at Infragistics.Win.UltraWinGrid.ScrollRegionBase.WillScrollbarBeShown()
   at Infragistics.Win.UltraWinGrid.ViewStyleBase.AddBandHeaders(ColScrollRegion csr, UltraGridBand band)
   at Infragistics.Win.UltraWinGrid.ViewStyleVertical.RecreateHeaderList(ColScrollRegion csr)
   at Infragistics.Win.UltraWinGrid.ColScrollRegion.RegenerateVisibleHeaders()
   at Infragistics.Win.UltraWinGrid.ColScrollRegionsCollection.InitializeMetricsHelper()
   at Infragistics.Win.UltraWinGrid.ColScrollRegionsCollection.InitializeMetrics()
   at Infragistics.Win.UltraWinGrid.UltraGridLayout.ApplyLoadedBands()
   at Infragistics.Win.UltraWinGrid.UltraGrid.Export(IUltraGridExporter exporter)
   at Infragistics.Win.UltraWinGrid.ExcelExport.UltraGridExcelExporter.Export(UltraGrid grid, Worksheet worksheet, Int32 startRow, Int32 startColumn)
   at Infragistics.Win.UltraWinGrid.ExcelExport.UltraGridExcelExporter.Export(UltraGrid grid)
   at Infragistics.Win.UltraWinGrid.ExcelExport.UltraGridExcelExporter.Export(UltraGrid grid, String fileName)