A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.

Hello Sir ,

i was creating some connection string but he occurred some error :

An attempt to attach an auto-named database for file C:\Program Files\Common Files\Microsoft Shared\DevServer\10.0\AMASDB.mdf failed. A database with the same name exists, or specified file cannot be opened, or it is located on UNC share.

my connection string :

<connectionStrings>
    <add name="AMAS.Data.ConnectionString" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\AMASDB.mdf;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient" />
    <add name="AMASDataConnectionString" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\AMASDB.mdf;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient" />
  </connectionStrings>

Global.aspx page:

void Application_Start(object sender, EventArgs e)
    {
        // Code that runs on application startup
         System.Data.SqlClient.SqlDependency.Start(ConfigurationManager.ConnectionStrings["AMAS.Data.ConnectionString"].ConnectionString);
    }

    void Application_End(object sender, EventArgs e)
    {
        //  Code that runs on application shutdown
        System.Data.SqlClient.SqlDependency.Stop(ConfigurationManager.ConnectionStrings["AMAS.Data.ConnectionString"].ConnectionString);
    }