how to retrieve image from database

hi
could anyone help me how to retrieve image from database..........i just loaded image without any error but i cant retrive im getting error message .
here is the code and error message:
Default.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Store & Display Images From Database</title>
    <style type="text/css">
    body
    {
        font-family:Verdana;
   &n ...