private void FilterContractButton_Click(object sender, EventArgs e) { if (PeriodCheckBox.Checked) { if (ContractCalendarTo.SelectionEnd < ContractCalendarFrom.SelectionEnd) { ErrorContractLabel.Visible = true; return; } else { ErrorContractLabel.Visible = false; } ClientPayments.CheckClientContractAndPeriod(ClientContractComboBox.SelectedValue.ToString(), ContractCalendarFrom.SelectionEnd, ContractCalendarTo.SelectionEnd, ClientContractCheckBox.Checked); } }