private void button2AddSales_Click(object sender, EventArgs e) { if (textBox2_addSales.Text == "") { MessageBox.Show("Please, input how much money you want to add as Sales"); } else { int r = controllerObj.AddSales((int)comboBox1.SelectedValue, Convert.ToDouble(textBox2_addSales.Text)); if (r > 0) { MessageBox.Show("Sales added successfuly"); } else { MessageBox.Show("Error adding Sales"); } } }