check if value exists in pivot table

I have a macro that inserts the value of the active cell into cell A1 of the
same worksheet. Pivot tables on other worksheets are then filtered by that
value. Now I need to write some error handling so that if the value of the
active cell is not contained in the pivot table, it exits the procedure.
Here is the code I have so far.

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Application.ScreenUpdating = False
If ActiveCell.Value = "" Then
Exit Sub
Else
'insert project name (value of column A of active row) into cell A1
Range("A1") = Cells(ActiveCell.Row, "A").Value
'insert staff name (value of column B of active row) into cell A2
Range("A2") = Cells(ActiveCell.Row, "B").Value

'refresh all pivot tables
ThisWorkbook.RefreshAll
End If
Application.ScreenUpdating = True
End Sub

Any help would be greatly appreciated.

- Mica