Pivot Table Update - Problem

[Sloopy]

I have a problem relating to updating pivot tables from within vba.

The following works fine when called from a command button:

Sub RefreshPivotTables()
    
    Dim ws As Worksheet
    Dim pt As PivotTable
    
    For Each ws In ThisWorkbook.Worksheets
        For Each pt In ws.PivotTables
            pt.RefreshTable
        Next pt
    Next ws
    
End Sub

However when I call the sub from another sub in VBA it results in #Ref! errors in the results:

Call RefreshPivotTables

Are there any subtleties when refreshing data in pivot tables? I have tried adding pt.update to see if this helps but again the puzzling thing is that the same routine works fine when called from a command button but not when calling the sub from another sub.

Any help is much appreciated and thanks for providing such a great forum.