Macro to filter Pivot not working

Hi,

I've created a simple macro to change the filters of one of the pivot charts. However, when i run the macro, i get the following error; "Run-time error 1004. Unable to get the Pivot Tables property of the Worksheet Class"

Here's the code:

    
With ActiveSheet.PivotTables("Pivottabell1").PivotFields("University")
        .PivotItems("UIO").Visible = False
        .PivotItems("HIO").Visible = True
End With

Ideally, i would extend the macro to change the same field ("University") on all four pivot charts on the sheet, but i'm trying to get it to work with one first.

Thanks in advance.