Trigger Worksheet Change by copy and paste

The following code seems to work fine if the user selects a value from the drop down cell in column T, but if that user then copies and pastes his selection into subsequent cells, it appears that the event is not trigger so the data validation does not get added to column S as it should. Could anyone provide some assistance to this? I am sure my code is a little redundant (still trying to learn all this). This code is on the actual sheet tab, just in case you didn't already know that.

Private Sub Worksheet_Change(ByVal Target As Range)

    If Not Intersect(Target, Range("T:T")) Is Nothing Then
        If Target.Count > 1 Then
            Me.Unprotect Password:="password"
            Application.EnableEvents = False
            Target.Offset(0, -1).Validation.Delete
            Target.Offset(0, -1).Locked = True
            Application.EnableEvents = True
            Me.Protect Password:="password", AllowFiltering:=True
            Exit Sub
        Else:
            If Target.Value <> """" Then
            Me.Unprotect Password:="password"
            Application.EnableEvents = False
                If Target.Offset(0, 7).Value = "P" Then
                    Target.Offset(0, -1).Validation.Add Type:=xlValidateList, Formula1:="ITR1,ITR2,ITR3,ITR4,ITR5,ITR6,ITR7,ITR8,ITR9,ITR10,ITR11,ITR12,ITR13,ITR14,ITR15"
                    Target.Offset(0, -1).Locked = False
                Else: Target.Offset(0, -1).Validation.Delete
                    Target.Offset(0, -1).Locked = True
                End If
            End If
            Application.EnableEvents = True
            Me.Protect Password:="password", AllowFiltering:=True
        End If
    End If

End Sub