Formatting - Calculated Field in Pivot Table.

I have a report that I am creating using a pivot table. Everything works great except formatting. The pivot table can be expanded and contracted to drill down into different layers and when this happens, formatting issues arise. To combat this, I use a button to run the macro at the bottom to derive the formatting from the source data. Unfortunately, there are calculated fields that do not have source data, and thus the formatting is still an issue.

Two questions:

How can I best fix the calculated field formatting issue?
Is there an event I can tie the macro to that will run if fields are expanded or contracted?

Thanks,
Kurt

Sub SourceFormat()

Dim oPivotTable As PivotTable
Dim oPivotFields As PivotField
Dim oSourceRange As Range
Dim strLabel As String
Dim strFormat As String
Dim i As Integer

On Error GoTo Err1

'Identify PivotTable and capture source Range
    Set oPivotTable = ActiveSheet.PivotTables(ActiveCell.PivotTable.Name)
    Set oSourceRange = Range(Application.ConvertFormula(oPivotTable.SourceData, xlR1C1, xlA1))

'Refresh PivotTable to synch with latest data
    oPivotTable.PivotCache.Refresh

'Start looping through the columns in source range
    For i = 1 To oSourceRange.Columns.Count
    
    'Trap the column name and number format for first row of the column
        strLabel = oSourceRange.Cells(1, i).Value
        strFormat = oSourceRange.Cells(2, i).NumberFormat
    
    'Now loop through the fields PivotTable data area
        For Each oPivotFields In oPivotTable.DataFields
   
        'Check for match on SourceName then appply number format if there is a match
            If oPivotFields.SourceName = strLabel Then
            oPivotFields.NumberFormat = strFormat
            
        'Bonus:  Change the name of field to Source Column Name
            oPivotFields.Caption = strLabel & " "
            End If
        
        Next oPivotFields
    Next i

Exit Sub

'Error stuff
Err1:
If Err.Number = 1004 Then
MsgBox "Cursor must be inside of a pivot table."
Else
MsgBox Err.Number & vbCrLf & Err.Description
End If

End Sub