Using vba code with undo option

Hi
I have this code in one of my sheet

Private Sub Worksheet_Change(ByVal Target As Range)
    If Range("B6").Value = "All" Then
        Rows("55:65").EntireRow.Hidden = True
    Else
        Rows("55:65").EntireRow.Hidden = False
    End If
End Sub

The problem is once i put it in my sheet, The undo button greys out
Is there any possibility to use the undo button after having this code in the sheet?
Can anyone alter the vba code so as to enable the undo click?

Thanks in advance!!