Dear Gurus,
I'm having troubles in replicating a set of code in the same Sub.
Basically (with the support of this forum) I've been able to complete a code section which is entitled to add some columns to a table on the basis of a difference in months.
Now I'm trying to make the same operation on another sheet/ table and I will need to make the same at least on some other worksheets.
But, I'm getting an "Application-defined or object-defined error".

Here below the code:

Private Sub InitializeProject_Click()


Dim ws1, ws3, ws4 As Worksheet
Dim dur, dur2 As Variant
Dim i, j As Long
Dim table3, table4 As ListObject
Dim stdate, stdate2 As Date
Dim colCount, colCount1 As Integer


Set ws1 = Worksheets(1)
dur = ws1.Range("C8").Value
stdate = ws1.Range("C6").Value


'Tab Effort


Set ws3 = Worksheets(3)
Set table3 = ws3.ListObjects("EffortResources")


With table3
    For i = 1 To dur
        .ListColumns.Add
        colCount = .ListColumns.Count
        .ListColumns(colCount).Range(1).Select
        Selection.NumberFormat = "mmm\-yyyy"
        Selection.Value = DateAdd("m", i - 1, stdate)
    Next i
End With


'Tab Other Costs


Set ws4 = Worksheets("Other Costs")
Set table4 = ws4.ListObjects("Costs")


With table4
    For j = 1 To dur
        .ListColumns.Add
        colCount1 = .ListColumns.Count
        .ListColumns(colCount1).Range(1).Select
        Selection.NumberFormat = "mmm\-yyyy"
        Selection.Value = DateAdd("m", j - 1, stdate)
    Next j
End With


End Sub
Could you please advise?

Thanks in advance,
A.