How to process Target to account for >1 cell in the range:
Private Sub Worksheet_Change(ByVal Target As Range)
Dim c as Range
For each c in Target.cells
If c.Column = 11 Then
c.Offset(0, 1).Value = Now()
End If
Next c
End Sub
or:
Private Sub Worksheet_Change(ByVal Target As Range)
Dim rng as Range
Set rng = Application.Intersect(Target, Me.Columns(11))
If not rng is nothing then
rng.Offset(0, 1).Value = Now()
End If
End Sub
Also a good idea to disable events before you update the spreadsheet from your Change sub (otherwise you just re-trigger the event with your update). Use
Application.EnableEvents=False
then set back to True when done (don't forget that part!)