Excel VBA - Referencing Range using Cells - vba

Question

I am trying to dynamically add validation (using DataValidation:List) to ranges in a worksheet. I recorded a macro that produced the following code:
With Worksheets("Clusters").Range("C2:C100").Validation
.Delete
.Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, Operator:= _
xlBetween, Formula1:="=Managers"
.IgnoreBlank = True
.InCellDropdown = True
.InputTitle = ""
.ErrorTitle = ""
.InputMessage = ""
.ErrorMessage = ""
.ShowInput = True
.ShowError = True
End With
This was working fine for the static range C2:C100, but the column may not be always be C. I have a variable cMANFCM that contains the column number. I tried to edit the code to use this:
With Worksheets("Clusters").Range(Cells(2,cMANFCM), Cells(100, cMANFCM)).Validation
.Delete
.Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, Operator:= _
xlBetween, Formula1:="=Managers"
.IgnoreBlank = True
.InCellDropdown = True
.InputTitle = ""
.ErrorTitle = ""
.InputMessage = ""
.ErrorMessage = ""
.ShowInput = True
.ShowError = True
End With
Why doesn't this work and how do I fix it?

Answer 1

Your code works on mine - I've added a line to delete all existing validation and it does create new validation without throwing an error:
Lots of the validation arguments can probably be ignored...and you've got a choice of how to reference the sheet/range when other sheets are active:
Option Explicit
Sub control()
'Call changeValidation(4)
'Call changeValidationPAlbert(5)
Call changeValidationTWilliams(6)
End Sub
Sub changeValidation(cMANFCM As Integer)
With Excel.ThisWorkbook.Worksheets("Clusters")
.Cells.Validation.Delete
.Range(.Cells(2, cMANFCM), .Cells(100, cMANFCM)).Validation.Add _
Type:=xlValidateList, _
AlertStyle:=xlValidAlertStop, _
Operator:=xlBetween, _
Formula1:="=managers"
End With
End Sub
Sub changeValidationAlbert(cMANFCM As Integer)
With Excel.ThisWorkbook.Worksheets("Clusters")
.Cells.Validation.Delete
.Range("A2:A100").Offset(, cMANFCM - 1).Validation.Add _
Type:=xlValidateList, _
AlertStyle:=xlValidAlertStop, _
Operator:=xlBetween, _
Formula1:="=managers"
End With
End Sub
Sub changeValidationTWilliams(cMANFCM As Integer)
With Excel.ThisWorkbook.Worksheets("Clusters")
.Cells.Validation.Delete
.Cells(2, cMANFCM).Resize(100, 1).Validation.Add _
Type:=xlValidateList, _
AlertStyle:=xlValidAlertStop, _
Operator:=xlBetween, _
Formula1:="=managers"
End With
End Sub