Design-Time Attributes are not working

I have tried to add Design-Time Attributes to my controls, but they do not
seem to be making any difference. Here is an example:

<ToolboxData("<{0}:Parameter runat=server/>")> _
Public Class Parameter : Inherits System.Web.UI.Control
End Class

When I drag it from the ToolBox, I still get the following:

<NJS:Parameter ID="Parameter1" runat="server"></NJS:Parameter>

I know that it is possible to specify what comes up when dragging from the
ToolBox, because many of the controls that come with ASP.NET include
different things (Image is self-closing, Panel includes Height & Width, and
other controls have stuff as well). Can somebody tell me what I'm doing
wrong here? Thanks.
--
Nathan Sokalski
(E-Mail Removed)
http://www.nathansokalski.com/