VBA - Blattschutz

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
ActiveSheet.Unprotect ("123")
If Target.Count > 1 Then Exit Sub
If Not Intersect(Target, Me.Range("D21:M81")) Is Nothing Then
With Me.Cells(Target.Row, 3)
On Error Resume Next
OldRange.Interior.Color = OldColor
On Error GoTo 0
OldColor = .Interior.Color
.Interior.Color = RGB(0, 255, 0)
End With
Set OldRange = Me.Cells(Target.Row, 3)
Else
OldRange.Interior.Color = OldColor
End If
ActiveSheet.Protect ("123")
End Sub