Big problem with my app, the menu goes in conflict with the rest of the app

[grafic.web]

Hi, is more than a week that i try to resolve this error on my app but i can't...

The problem is the following :

I have a menu and submenu table and i show this records in this mageMenu.chstml (list of menus and submenus to generate the menubar of my site) called in my _Layout.cshtml THIS IS WORKING FINE

What is not working are all the pages where the tables called are linked to the tables menu and submenu... (Example My table Magazine and the table FORUM both have a menuID and submenuID), when i run the pages with the list of this 2 tables , the app goes in error :

à System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction

Erreur  1   Impossible de convertir implicitement le type 'System.Linq.IQueryable<CollectionHair.Models.Magazine>' en 'CollectionHair.Models.Magazine'. Une conversion explicite existe (un cast est-il manquant ?)  C:\FRANCESCO\Project\CollectionHair\CollectionHair\Controllers\MagazineController.cs    26  29  Collecti

Erreur  2   'CollectionHair.Models.Magazine' ne contient pas une définition pour 'ToList' et aucune méthode d'extension 'ToList' acceptant un premier argument de type 'CollectionHair.Models.Magazine' n'a été trouvée (une directive using ou une référence d'assembly est-elle manquante ?)  C:\FRANCESCO\Project\CollectionHair\CollectionHair\Controllers\MagazineController.cs    34  25  CollectionHair

All the rest of the app working well, i mean all the other pages calling the tables that are not linked to the menu and submenu table ARE WORKING.

I'm going to put here the link to download my app and see if you understand why the error occurs :

Click Here

Thanks for your help