Adding an additional item to a dropdownlist datasource from C#

I possessDropDownList that is connected to aDataSource inside the ASPX page. When the page loads, I still need to add one more thing.

I'm Code:

<asp:LabelDropDownList ID="ddlVisualTemplate" runat="server" LabelText="Visual Template:"      DataSourceID="VisualTemplateDataSource" DataTextField="Name" DataValueField="Id" AutoPostBack="true" OnSelectedIndexChanged="ddlVisualTemplate_SelectedIndexChanged"/>                         

<asp:EntityDataSource ID="VisualTemplateDataSource" runat="server" 
     ConnectionString="name=Entities" 
     DefaultContainerName="Entities" EnableFlattening="False" 
     EntitySetName="tbEmailVisualTemplates">

And I'm attempting to add this additional item:

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            ddlVisualTemplate.Items.Add(new ListItem("None", string.Empty));
        }
    }

The code runs through it when I debug it. But When the page is displayed dropdown doesn't contain"None" .