How to show the summary value of a summary row in caption row in WinForms GridGroupingControl?

//To add summary.
GridSummaryColumnDescriptor summaryColumnDescriptor = new GridSummaryColumnDescriptor();
summaryColumnDescriptor.Name = "Category";
summaryColumnDescriptor.DataMember = "CategoryID";
summaryColumnDescriptor.Format = "{Average:#.00}";
summaryColumnDescriptor.SummaryType = SummaryType.DoubleAggregate;        
GridSummaryRowDescriptor summaryRowDescriptor = new GridSummaryRowDescriptor();
summaryRowDescriptor.Name = "Average of CategoryID column";           
summaryRowDescriptor.SummaryColumns.Add(summaryColumnDescriptor);
gridGroupingControl1.TableDescriptor.SummaryRows.Add(summaryRowDescriptor);            
this.gridGroupingControl1.TopLevelGroupOptions.ShowSummaries = false;
 
//To retrieve summaryrow name.
string summaryRowName = summaryRowDescriptor.Name;
//To retrieve summarycolumn name.
string summaryColumnName = summaryColumnDescriptor.Name;
//Setting caption text. 
this.gridGroupingControl1.ChildGroupOptions.CaptionText = "{Category} {RecordCount} Items at Average {" + summaryRowName + "." + summaryColumnName + "}" ;

'To add summary.
Dim summaryColumnDesecriptor As New GridSummaryColumnDescriptor()
summaryColumnDesecriptor.Name = "Category"
summaryColumnDesecriptor.DataMember = "CategoryID"
summaryColumnDesecriptor.Format = "{Average:#.00}"
summaryColumnDesecriptor.SummaryType = SummaryType.DoubleAggregate
Dim summaryRowDescriptor As New GridSummaryRowDescriptor()
summaryRowDescriptor .Name = "Summary Row"
summaryRowDescriptor .SummaryColumns.Add(summaryColumnDescriptor)
gridGroupingControl1.TableDescriptor.SummaryRows.Add(summaryRowDescriptor)
Me.gridGroupingControl1.TopLevelGroupOptions.ShowSummaries = False
 
'To retrieve summaryrow name.
Dim summaryRowName As String = summaryRowDescriptor.Name
'To retrieve summarycolumn name.
Dim summaryColumnName As String = summaryColumnDescriptor.Name
'Setting caption text. 
Me.gridGroupingControl1.ChildGroupOptions.CaptionText = "{Category} {RecordCount} Items at Average {" & summaryRowName & "." & summaryColumnName & "}"