private void btnLogin_Click(object sender, EventArgs e) { StockServiceClient service = new StockServiceClient(); if (service.AuthenticateUser(txtUserName.Text.Trim(), txtPassword.Text)) { ParentForm.CurrentUser = txtUserName.Text.Trim(); this.DialogResult = DialogResult.OK; BackToParent(); } else { lblError.Text = "Foutieve Gebruikersnaam/Paswoord"; lblError.Visible = true; } }