VBA - Lock Pivot Table w/ Calculated Fields

[gehusi]

I am using the following standard bit of code to loop through the worksheets and lock each pivot table's structure.

Sub LockPivotTable()
Dim pt As PivotTable
Dim pf As PivotField
Dim ws as Worksheet

For Each ws in ActiveWorkbook.Worksheets
Set pt = ActiveSheet.PivotTables(1)
      With pt
             .EnableWizard = False
             .EnableDrilldown = False
             .EnableFieldList = False
             .EnableFieldDialog = False
             .PivotCache.EnableRefresh = True
                  For Each pf In pt.PivotFields
                         With pf
                                .DragToPage = False '(1)
                                .DragToRow = False
                                .DragToColumn = False
                                .DragToData = False
                                .DragToHide = False
                         End With
                 Next pf
      End With
Next ws
End Sub

The code is breaking at (1), and I believe it may be because I have a few calculated fields. Any help is appreciated.