ช่วยด้วยครับมีปัญหาตอน Add ข้อมูลลง Database ข้ามขั้นเฉยเลย T_T

private void button1_Click(object sender, EventArgs e)
        {            
            string sql = "Select idseat from book where idseat = @IS";
            cmd = new SqlCommand(sql, conn);
            cmd.Parameters.Clear();
            cmd.Parameters.Add("@IS", SqlDbType.NChar).Value = textBox4.Text.Trim();
            adapter = new SqlDataAdapter(cmd);
            ds = new DataSet();
            int p = adapter.Fill(ds, "b");
            if (p == 0)
            {
                open_conn();
                tr = conn.BeginTransaction();
                try
                {                    
                    sql = "Insert into book (idticket, dateticket, idbus, idseat, cuscode) values(@idt, @date, @idb, @ids, @code)";
                    cmd = new SqlCommand(sql, conn);
                    cmd.Transaction = tr;
                    cmd.CommandType = CommandType.Text;
                    cmd.CommandText = sql;
                    cmd.Parameters.AddWithValue("idt", textBox5.Text);
                    cmd.Parameters.AddWithValue("date", dateTimePicker1.Text);
                    cmd.Parameters.AddWithValue("idb", textBox2.Text);
                    cmd.Parameters.AddWithValue("ids", textBox4.Text);
                    cmd.Parameters.AddWithValue("code", textBox1.Text);

                    cmd.ExecuteNonQuery();
                    tr.Commit();
                    MessageBox.Show("Saved");
                    loadData();
                    clearData();
                    this.Hide();
                    FormMenuMain f = new FormMenuMain();
                    f.Show();
                }
                catch (Exception)
                {
                    MessageBox.Show("Identify yet");
                    conn.Close();
                }
            }
            else
            {
                sql = "Select idbus from book where idseat = @IdB";
                cmd = new SqlCommand(sql, conn);
                cmd.Parameters.Clear();
                cmd.Parameters.Add("@IdB", SqlDbType.NChar).Value = textBox2.Text.Trim();
                adapter = new SqlDataAdapter(cmd);
                ds = new DataSet();
                int pp = adapter.Fill(ds, "b2");
                if (pp == 0)
                {
                    open_conn();
                    tr = conn.BeginTransaction();
                    try
                    {                        
                        sql = "Insert into book (idticket, dateticket, idbus, idseat, cuscode) values(@idt, @date, @idb, @ids, @code)";
                        cmd = new SqlCommand(sql, conn);
                        cmd.Transaction = tr;
                        cmd.CommandType = CommandType.Text;
                        cmd.CommandText = sql;
                        cmd.Parameters.AddWithValue("idt", textBox5.Text);
                        cmd.Parameters.AddWithValue("date", dateTimePicker1.Text);
                        cmd.Parameters.AddWithValue("idb", textBox2.Text);
                        cmd.Parameters.AddWithValue("ids", textBox4.Text);
                        cmd.Parameters.AddWithValue("code", textBox1.Text);

                        cmd.ExecuteNonQuery();
                        tr.Commit();
                        MessageBox.Show("Saved");
                        loadData();
                        clearData();
                        this.Hide();
                        FormMenuMain f2 = new FormMenuMain();
                        f2.Show();
                    }
                    catch (Exception)
                    {
                        MessageBox.Show("Have a book (bus)");
                        conn.Close();
                    }
                }
                else
                {
                    MessageBox.Show("Have a book"); clearData();                    
                }
            }
        }