这段代码怎么不能实现？

[chinaonl]

Public Class Class1
Inherits TextBox
Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
e.Graphics.DrawRectangle(Pens.Black, 0, 0, Me.Width, Me.Height)
End Sub
End Class

我的意思是从TEXTBOX中继承下来，重写它的ONPAINT，为什么这段代码不能实现它还是以原来的样式显示出来，这是为什么。

[sx_lxh]

Public Class Class1
Inherits TextBox
Public Sub New()
setstyle(ControlStyles.UserPaint,True)
End Sub
Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
e.Graphics.DrawRectangle(Pens.Black, 0, 0, Me.Width, Me.Height)
End Sub
End Class