I'm trying to retrieve an application from my database. I have a Data Context in my app called AppSecurityDataDataContext. Here's my query:

{ 
    AppSecurityDataDataContext dc = new AppSecurityDataDataContext();
    var app = from a in dc._Applications
                where a.ApplicationId = ApplicationID
                select a;

}

I'm getting "Could not find an implementation of the query pattern for source type 'System.Data.Linq.Table<AppSecurity._Application>'. 'Select' not found. Are you missing a reference to 'System.Core.dll' or a using directive for 'System.Linq'?"

I have the using statement in my class. This other method works:

public static void AddApplication(Application Application)
{
    _Application app = new _Application
    {
        ApplicationName = Application.ApplicationName
    };

    _DataContext._Applications.InsertOnSubmit(app);

    try
    {
        _DataContext.SubmitChanges();
    }
    catch (Exception e)
    { 
    }
}

Anyone see what's wrong here?