Server Error in '/' Application, Resource cannot be found

Hi is someone encountered . error is asp.net 4.0? I created a login page for my DVD selling website project and provided a username and password authentication for users. I also had created username and password for an admin access. I set the default page to Home.aspx to show all information of DVD's i have in the database. At first when i run the website it work's fine it shows the front page and when i try to log-in the error occurs. I checked the name of the database in each page, make it is right such as: string dbconnectionString=ConfigurationManager.ConnectionStrings["DVDDB"].ConnectionString; and so it is correct.

Here is my code to provide security to the site, i don't think it cause i already fix the name of the server and the database on it. Just showing in case you might see an error that i don't.

**

<compilation debug="true" targetFramework="4.0" />
 <authentication mode="Forms">   <forms timeout="30">
   <!---This will setup the admin username and password that has credentials to access the website-->
    <credentials passwordFormat ="MD5">

      <user name ="admin" password ="21232F297A57A5A743894A0E4A801FC3" /><!--This include hash tag-->

    </credentials>

</forms>  </authentication>

 <authorization> 

<allow users ="?" /> 

</authorization>

<authorization>

<deny users ="?"/>

</authorization>

**

**<connectionStrings>
  <add name="DVDDB" connectionString="Server=JOHN-PC;
  Database= DVDDB;
  Integrated Security=True" providerName = "System.Data.SqlClient"/>
</connectionStrings>

**

I also check the internet for answer but it seems that the error occurs on different scenario. If someone had the exact problem like i do, i would be appreciate if you share your experiences with me. Thank you in advance