SaveChanges() doesn't work (Entity Framework, C#, Windows Forms)

I have a very weird problem. I try to submit changes to the d开发者_如何学运维atabase (using Entity Framework) like this:

private ProfEntities pe = new ProfEntities();
//...
var row = pe.Irregular_Veebs.Single(e => e.id == id); //selecting one row by id
row.seen = true; //changing seen property to true
pe.SaveChanges();

it looks simple but it doesn't work: when I look in Database Explorer, the "seen" field is still false. AM I doing something wrong?

If you're using file database you probably explore db which is in your solution folder. To see changes you should open db from Release or Debug folder