Copy Excel formula to last row on multiple work sheets - vba

Question

I have a workbook which has multiple worksheets that vary in name but the content structure of each sheet remains the same. There is only one sheet name that is always constant pie.
I am trying to apply a formula in cell N2 and then copy the formula down to the last active row in all the worksheets except the one named pie
The code I have so far is works for one loop but then i get an error "AutoFill method of Range Class failed"
I have used
Lastrow = Range("M" & Rows.Count).End(xlUp).Row
to determine the last row as column M is always complete.
Any help to complete this would be very much appreciated
Code i have is:
Sub ConcatForm()
Dim wSht As Worksheet
Lastrow = Range("M" & Rows.Count).End(xlUp).Row
Application.ScreenUpdating = False
For Each wSht In Worksheets
If wSht.Name <> "Pie" Then
wSht.Range("N2").FormulaR1C1 = "=CONCATENATE(RC[-3],RC[-2],RC[-1])"
wSht.Range("N2").AutoFill Destination:=Range("N2:N" & Lastrow)
End If
Next wSht
Application.ScreenUpdating = True
End Sub

Answer 1

You don't need to use Autofill to achieve this.
Just apply your formulas directly to your range and use relative references, i.e. K2, rather than absolute references, i.e. $K$2. It will fill down and update the formula for you.
Make sure you are fully qualifying your references. For example, see where I have used ThisWorkbook and the update to how lastrow is initialized. Otherwise, Excel can get confused and throw other errors.
Your lastrow variable hasn't been dimensioned so it is an implicit Variant. You'd be better off dimensioning it explicitly as a Long.
Sub ConcatForm()
Application.ScreenUpdating = False
Dim wSht As Worksheet
Dim lastrow As Long
With ThisWorkbook.Worksheets("Sheet1") 'which worksheet to get last row?
lastrow = .Range("M" & .Rows.Count).End(xlUp).Row
End With
For Each wSht In ThisWorkbook.Worksheets
If wSht.Name <> "Pie" Then
wSht.Range("N2:N" & lastrow).Formula = "=CONCATENATE(K2,L2,M2)"
End If
Next wSht
Application.ScreenUpdating = True
End Sub

Answer 2

you were just one wSht reference away from the goal:
Sub ConcatForm()
Dim wSht As Worksheet
lastRow = Range("M" & Rows.count).End(xlUp).row '<--| without explicit worksheet qualification it will reference a range in the "active" sheet
Application.ScreenUpdating = False
For Each wSht In Worksheets
If wSht.Name <> "Pie" Then
wSht.Range("N2").FormulaR1C1 = "=CONCATENATE(RC[-3],RC[-2],RC[-1])"
wSht.Range("N2").AutoFill Destination:=wSht.Range("N2:N" & lastRow) '<--| this will reference a range in 'wSht' worksheet
End If
Next
Application.ScreenUpdating = True
End Sub

Answer 3

Use following sub...
Sub ConcatForm()
Dim wSht As Worksheet
Lastrow = Range("A" & Rows.Count).End(xlUp).Row
Application.ScreenUpdating = False
For Each wSht In Worksheets
With wSht
If .Name <> "Pie" Then
.Select
.Range("N2").FormulaR1C1 = "=CONCATENATE(RC[-3],RC[-2],RC[-1])"
.Range("N2").AutoFill Destination:=Range("N2:N" & Lastrow)
End If
End With
Next wSht
Application.ScreenUpdating = True
End Sub