Taking backup from DataBase (LINQ)?

[M-Dayyan]

Hi.
I've added a SQL database to my project. It's beside of the exe file in SQL folder.
I was using SQL to LINQ.
Now I wanna get a backup from it with C#.
I'm using following method :

public static void GetBackUp()
{
    if (!Directory.Exists(StaticVariables.BackUPFolder))
        Directory.CreateDirectory(StaticVariables.BackUPFolder);

    using (RezaRestaurant.SQL.DataClasses1DataContext dbc = new RezaRestaurant.SQL.DataClasses1DataContext())
    {
        dbc.ExecuteCommand(@"BACKUP DATABASE " + dbc.Mapping.DatabaseName + " TO DISK='c:\aaa.bak'");//Exception
    }
} 

But I've received the below Exception



Could you please guide me, how I can resolve it ?
Thanks.