Another Idea might be, if it is not finding the code file. verify the spelling and that it can find it.
I don't understand why it works, but it just worked for me using VB.Net
I used a stock VS2008 build for a webapplication.
Dropped Into the the deault aspx:
<asp:Label ID="Label1" runat="server" Text="Case Number:" ></asp:Label>
<asp:Label ID="m" runat="server" ></asp:Label><br /><br />
and dropped in below to the default aspx vb file:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
m.Text = "StuffToShow"
and the result was