<obout:OboutTextBox runat="server" ID="txt1" /><obout:Calendar ID="cal1" runat="server" DatePickerMode="true" />
protected void Page_Load(object sender, EventArgs e) { cal1.TextBoxId = txt1.ClientID; }
Protected Sub Page_Load(By Val sender As Object, ByVal e As EventArgs) cal1.TextBoxId = txt1.ClientID End Sub