dbContext Not Contain Refresh Method

hi i want to use Refresh Method in dbContext For Update DataBase but is not...

<pre lang="c#">

dbContext.Context.Refresh(RefreshMode.StoreWins, dbContext.Context.Products);

</pre>

i get error :

Error   1   'Shop.ShopEntities' does not contain a definition for 'Refresh' and no extension method 'Refresh' accepting a first argument of type 'Shop.ShopEntities' could be found (are you missing a using directive or an assembly reference?)   D:\Ebook - Learning\My dcuments\Visual Studio 2012\Projects\Shop\Shop\F1_Person.cs  24  30  Shop


Please help me ...