Excel 2003 : Comparaison 2 colones avec insertion "blanc"

Sub compare_a_b()
rowcount = Cells(Cells.Rows.Count, "a").End(xlUp).Row
For I = 1 To rowcount
Range("a" & I).Select
firstcell = ActiveCell
firstcell = Trim(firstcell)
Range("b" & I).Select
secondcell = ActiveCell
secondcell = Trim(secondcell)
'MsgBox firstcell & " a"
'MsgBox secondcell & " b"
    If firstcell <> secondcell Then
    Addresse = ActiveCell.Address
    MsgBox "La cellule n'est pas egale: " & Addresse
    Exit Sub
    End If
Next
End Sub

Sub AlignerValeurs()
    Dim c1 As Range, c2 As Range
    For Each c1 In Range("A1:A" & Range("A" & Rows.Count).End(xlUp).Row)
        Set c2 = Range("B:B").Find(what:=c1, LookIn:=xlValues, lookat:=xlWhole, searchorder:=xlByRows)
        If c2 Is Nothing Then
           c1.Offset(, 1).Insert xlShiftDown
        End If
    Next c1
End Sub