ปัญหาการแสดงกข้อมูลจากฐานข้อมูล(dvg)มา comboboxครับ ไอดีมา แต่ไม่แสดงชื่อครับ

     Dim cs = From c In dbDokmai.doctors
                 Select c.doc_id, c.doc_name
        With cbb_doc
            .BeginUpdate()
            .DisplayMember = "doc_name"
            .ValueMember = "doc_id"
            .DataSource = cs.ToList()
            .EndUpdate
        End With

 Private Sub dgv_care_CellMouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellMouseEventArgs) Handles dgv_care.CellMouseUp
        If e.RowIndex = -1 Then Exit Sub
        With dgv_care
            txt_care_id.Text = .Rows.Item(e.RowIndex).Cells(0).Value.ToString()
            txt_sick.Text = .Rows.Item(e.RowIndex).Cells(1).Value.ToString()
            txt_detail.Text = .Rows.Item(e.RowIndex).Cells(2).Value.ToString()
            txt_pama.Text = .Rows.Item(e.RowIndex).Cells(3).Value.ToString()
            dtp_care.Text = .Rows.Item(e.RowIndex).Cells(4).Value.ToString()
            txt_cus_id.Text = .Rows.Item(e.RowIndex).Cells(5).Value.ToString()
            cbb_doc.Text = .Rows.Item(e.RowIndex).Cells(6).Value.ToString()  ' บรรทัดที่ให้ไปแสดงใน cbb ครับ
           
            txt_care_id.Focus()
            txt_care_id.SelectAll()

        End With

        txt_sick.ReadOnly = True
        txt_detail.ReadOnly = True
        txt_pama.ReadOnly = True



    End Sub