Sqlite and EntityFramework 6 Invalid cast on SqlConnection to EntityConnection

I'm facing a InvalidCastException (SqliteConnection to EntityConnection) and is driving me crazy because I don't find much information about it and the one I find simply doesn't work.

I guess is something wrong with the app.config file but I've try a lot of things without any result.

Also try changing the DbContext but with the same result, nothing.

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Here the app.config file

<entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework"/>
    <providers>
      <providers>
         <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
         <provider invariantName="System.Data.SQLite.EF6" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6" />
     </providers>
    </providers>
  </entityFramework>
  <system.data>
    <DbProviderFactories>
         <remove invariant="System.Data.SQLite.EF6" />
         <add name="SQLite Data Provider (Entity Framework 6)" invariant="System.Data.SQLite.EF6" description=".NET Framework Data Provider for SQLite (Entity Framework 6)" type="System.Data.SQLite.EF6.SQLiteProviderFactory, System.Data.SQLite.EF6" />
         <add name="SQLite Data Provider" invariant="System.Data.SQLite" description=".NET Framework Data Provider for SQLite" type="System.Data.SQLite.SQLiteFactory, System.Data.SQLite" />
     </DbProviderFactories>
  </system.data>
  <connectionStrings>
    <add name="MailServerDBConnectionString"
         connectionString="metadata=http://res*/Database.DatabaseEntities.MailServerDBModel.csdl|res*/Database.DatabaseEntities.MailServerDBModel.ssdl|res*/Database.DatabaseEntities.MailServerDBModel.msl;provider=System.Data.SQLite.EF6;provider connection string=&quot;data source=C:\MailServerDB.s3db&quot;"
         providerName="System.Data.SQLite" />
  </connectionStrings>

Here the DbContext:

public MailServerDBConnectionString()
        : base("name=MailServerDBConnectionString")
    {
    }

Here how I use it:

try
{
            using (MailServerDBConnectionString context = new MailServerDBConnectionString())
            {
                    var inbound = context.C_DIRECTION.Find("INBOUND");
            }
}
catch (Exception crap)
{
            throw new Exceptions.DBException("Still not f*cking working", crap);
}

I've try everything and I hope someone has face this problem before, any suggestions is always welcome, thanks for your time.