private void btn_login_click() { email = this.tb_email.Text.Trim(); password = this.tb_password.Text.Trim(); if (email == "") { lbl_message.Text = "*Please enter a valid email"; lbl_message.ForeColor = Color.Red; return; } if (password == "") { lbl_message.Text = "*Please enter a valid password"; lbl_message.ForeColor = Color.Red; return; } manager = SystemManager.Login(email, password); if (manager == null) { this.lbl_message.Text = "*Wrong email or password!"; this.lbl_message.ForeColor = Color.Red; return; } else { MessageBox.Show("Login is successful. Please wait a while...", "", MessageBoxButtons.OK, MessageBoxIcon.Information); } Microwave microwave = new Microwave(manager); microwave.Show(); this.Hide(); }