FileUpload.HasFile всегда возвращает false

Question

FileUpload.HasFile всегда возвращает false

<asp:FileUpload id="FileUploadControl" runat="server" style="width:240px;" /> 
     <br />
     <asp:Label runat="server" id="StatusLabel" text="" />
<asp:Button runat="server" ID="btn1" OnClick="btn1_Click" />

protected void btn1_Click(object sender, EventArgs e)
    {
        string filename = "";

        if (FileUploadControl.HasFile)
        {
            try
            {
                filename = Path.GetFileName(FileUploadControl.FileName);
                FileUploadControl.SaveAs(Server.MapPath("~/Uploads/") + filename);
                StatusLabel.Text = filename;
            }
            catch (Exception ex)
            { 
                string str = ex.Message;
            }
        }
    }