Intersect method does not appear to work with a Data Entry Form

Question

The following code works as expected when I enter data directly into the worksheet. However, when I enter data using a form the code does not work. What am I missing here?

Set KeyCells = Range("UpdatedRange")

If Not Intersect(KeyCells, Range(Target.Address)) _ Is Nothing Then

    Range("AE" & Target.Row & "") = Now

End If

End Sub

I expected the code to work with a form as well as when entering data directly into the worksheet