ListBox Base Class won't let me implement a LoadPostData function

[Ron Brown]

When I paste in the function declaration code from the VS.NET 2003
IPostBackDataHandler Interface [Visual Basic] help page and then simply end
the function, I get the following compiler error:

'System.Web.UI.IPostBackDataHandler.LoadPostData' is already implemented by
base class 'System.Web.UI.WebControls.ListBox' and cannot be implemented
again.

Code:
Public Overridable Shadows Function LoadPostData( postDataKey As
String, postCollection As System.Collections.Specialized.NameValueCollection)
_
As Boolean Implements IPostBackDataHandler.LoadPostData

End Function

My custom component renders a textbox and a listbox, so how do I get the
data back from both of these components?