hey everyone. in vb.net (express edition) im trying to change multiple button properties at the same time. if i want to change the button width, this works

Code:
        For i = 1 To 42
            With Calendar.Panel1.Controls("Button" & i)
                .width= 12
            End With
        Next
but if i want to change the button border, this wont work:

Code:
        For i = 1 To 42
            With Calendar.Panel1.Controls("Button" & i).FlatAppearance
                .bordersize = 12
            End With
        Next
whats the difference and how do i get it working?

thanks
jason