Formatting Expression Columns display

I am using a groupinggridcontrol. and would like to display an expression column as a percentage display. Regular columns from my datasource I can set the format of the column using the following: MyGrid.TableDescriptor.Columns[5].Appearance.AnyCell.Format = "#0 %"; However this does not work for columns created using Expressionfields e.g. ExpressionFieldDescriptor avgTps = new ExpressionFieldDescriptor( "Average TPS", "[Total TPS] / [TPS Counter]" ); mSummaryGrid.TableDescriptor.ExpressionFields.Add( avgTps ); So how do I set the format attribute for this column

Try specifying the ResultType on the ExpressionFieldDescriptor. this.gridGroupingControl1.TableDescriptor.ExpressionFields.Add("sum"); ExpressionFieldDescriptor fd = this.gridGroupingControl1.TableDescriptor.ExpressionFields["sum"]; fd.ResultType = "System.Double"; fd.Expression = "[Col2] + [Col3]"; this.gridGroupingControl1.TableDescriptor.Columns["sum"].Appearance.AnyCell.Format = "#0.00 %";