private void buttonAddCompany_Click(object sender, EventArgs e) { try { connectionDB.addCompanyToList(comboBoxCompany.Text, comboBoxEmail.Text, comboBoxList.Text); // Use method to add a company in the list comboBox1_SelectedIndexChanged(null, null); } catch (Exception er) { MessageBox.Show("Error, the list is not updated", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); MessageBox.Show(er.ToString()); } }