PivotTable.NullString Property (Excel)
Returns or sets the string displayed in cells that contain null values when the DisplayNullString property is True. The default value is an empty string (""). Read/write String.
Syntax
expression .NullString
expression A variable that represents a PivotTable object.
Example
This example causes the PivotTable report to display "NA" in cells that contain null values.
With Worksheets(1).PivotTables("Pivot1")
.NullString = "NA"
.DisplayNullString = True
End With