Custom Drop Down List Control in .NET 2.0

[Vi]

Hi,
I have a .NET 1.1 web application where I'm using a custom Drop Down List
control. The main thing it does - it's changing its color when it is selected.
Here's how I use it:
<lib:customdropdownlist id="lst1" runat="server" BackColorOn="128, 255, 128">
<asp:ListItem Value="1" Selected="True">-- Select --</asp:ListItem>
<asp:ListItem Value="2">No</asp:ListItem>
<asp:ListItem Value="3">Yes</asp:ListItem>
</lib:customdropdownlist>

Now I'm converting the applicatin to .NET 2.0 and I get the following error:
"Element 'ListItem' is not a known element. This can occur if there is a
compilation errorin the Web Site".

I don't have any other errors while compiling the solution.
Thanks.