PivotCache Refresh - Cell formula return #Value

Question

I have a pivot table created from external data source(access) that contain number of records for each hour on a weekly basis for an average period of 3 months. Just beside this pivot table, I've created a column that calculates the average number record for each hour for a day. (A week here is just 5 days - sat & sun don't count).

To achieve the above, I have created a UDF that counts the number of weeks from the pivot data field (Week_Ending). To ensure the code don't count ghost or non-existent weeks, I have used the pivotcache refresh in the UDF. This works perfectly, except it now gives #value (A value used in the formula is the wrong data type) in the cells where I expect the daily average. I have found no issue with the cell formula and works if a single week is selected from the field "Week_Ending" instead of ALL.

I have attached the code and cell function and an image of the issue.

Cells formula in Cell E6 and it is similar upto cell E29 (Hourly cell reference is incremented by 1 for each cell)

=IF($E$4=1,GETPIVOTDATA("CountOfCase_Id",$A$4,"HOURLY",A6)/5,GETPIVOTDATA("CountOfCase_Id",$A$4,"HOURLY",A6)/($E$4*5))

Vba UDF function

Option Explicit

Function WeekCount(InputVal As Variant) As Integer
Dim book1 As String, PivotName As String

    book1 = ThisWorkbook.Name

    With Workbooks(book1).ActiveSheet
        If InputVal = "(All)" Then
            PivotName = .PivotTables(1).Name
            .PivotTables(PivotName).PivotCache.MissingItemsLimit = xlMissingItemsNone
            .PivotTables(PivotName).PivotCache.Refresh
            WeekCount = .PivotTables(PivotName).PivotFields("WEEK_ENDING").PivotItems.Count

        Else
            WeekCount = 1
        End If
    End With
End Function

I appreciate any help. Excel version is 2003.

Answer 1

The problem turned out to be with

.PivotTables(PivotName).PivotCache.Refresh

in the UDF and not fixed with Application.Volatile. However @GSerg’s solution without p.update seems to have worked.