This is not as expected:
<%@ Page %>
<html>
<script runat="server">
void OnButtonClick (object o, EventArgs args)
{
Console.WriteLine ("called");
}
</script>
<body>
<form runat="server">
<input runat="server" id="reply" type="Button"<!-- instead of Submit-->
onserverclick="OnButtonClick" value="Reply">
</form>
</body>
</html>