How to Use VBA Reference Pivot Table on Access 2010 Subform

I’m getting a type miss match (error 13) on the indicated line show below.

Dim subFormPTbl As Form    ' the subform with pivot table
Dim PTbl As PivotTable     ' refers to pivot table
Dim PTblFld As PivotField  ' a column field in the pivot table
Set subFormPTbl = Me.SuformWithPivot.Form
Set PTbl = subFormPTbl.PivotTable  ' < === ERROR HAPPENS HERE
For Each PTblFld In PTbl.ColumnFields
   If PTblFld.Selected Then
   Debug.Print "Selected column field name is " & PTblFld.Name
   End If
Next

I have a main form with a subform. The subform refers to a form with a default view set to pivot table. All I need to do is to list the column fields that are selected by the user.