Wpf combo box not being populate with sqlite data

I have wpf combo box which I am trying to fill using the following codes. I found these exact codes from another stack follow here Attach a SQL database to ComboBox.ItemSource (WPF). Nothing gets populate into the combo box. I also would like to what code can I use to set selected value if I provide some value based on the companyID.

        private void fillComboBox()
        {

            try
            {
                getCon getMyCon1 = new getCon();
                SQLiteConnection con = getMyCon1.GetConnection();
                SQLiteCommand sqlcmd = new SQLiteCommand();
                SQLiteDataAdapter sqladp = new SQLiteDataAdapter();
                DataSet ds = new DataSet();


                sqlcmd.Connection = con;
                sqlcmd.CommandType = CommandType.Text;
                sqlcmd.CommandText = "Select * from company";
                sqladp.SelectCommand = sqlcmd;
                sqladp.Fill(ds, "defaultTable");
                DataRow nRow = ds.Tables["defaultTable"].NewRow();
                nRow["companyName"] = "Select A Company";
                nRow["companyID"] = "-1";
                ds.Tables["defaultTable"].Rows.InsertAt(nRow, 0);
                companyName.DataContext = ds.Tables["defaultTable"].DefaultView;
                //
                companyName.DisplayMemberPath = ds.Tables["defaultTable"].Columns[0].ToString();
                companyName.SelectedValuePath = ds.Tables["defaultTable"].Columns[1].ToString();

            }
            catch (Exception expmsg)
            {

            }
            finally
            {
                //sqladp.Dispose();
                //sqlcmd.Dispose();
            }
   }