private void cmbx_projects_SelectedIndexChanged(object sender, EventArgs e) { checkedListBoxWorkers.Items.Clear(); btn_addProjectToWorker.Visible = true; lbl_worker.Visible = true; List <User> workers = UserRequests.getSimpleWorkersNotInProject((cmbx_projects.SelectedItem as Project).ProjectId); if (workers != null) { checkedListBoxWorkers.DisplayMember = "UserName"; foreach (User worker in workers) { checkedListBoxWorkers.Items.Add(worker); } } checkedListBoxWorkers.Visible = true; }