seme1.DataBindings.Clear();
seme1.DataBindings.Add("Text", dtRatinSemYear, "rati_sem1");

               seme1.DataBindings.Clear();
                bindingRatinSemYear.DataSource = dtRatinSemYear;
                seme1.Visible = false;
                Binding bindseme1 = new Binding("Text", bindingRatinSemYear, "rati_sem1", true);
                bindseme1.ControlUpdateMode = ControlUpdateMode.OnPropertyChanged;
                bindseme1.DataSourceUpdateMode = DataSourceUpdateMode.OnPropertyChanged;
                seme1.DataBindings.Add(bindseme1);
                seme1.Visible = true;