LINQ dropdownlist bağlamak

okulDataContext okul = new okulDataContext();
ogrenciler ogrs = new ogrenciler();
var ogrenci = from ogr in okul.ogrencilers
where ogr.ad == "Erman"
select new { ogr.ad, ogr.soyad };

ddl1.DataValueField = "ad";
ddl1.DataTextField = "soyad";
ddl1.DataSource = ogrenci.ToList();
ddl1.DataBind();