private void chkNewTrackNumber_CheckedChanged(object sender, EventArgs e)
        {
            try
            {
                if (chkNewTrackNumber.Checked)
                {
                    txtTrackNumber.EditValue = null;
                    txtTrackNumber.Enabled   = false;

                    ValidationProvider.RemoveControlError(txtTrackNumber);
                }
                else
                {
                    txtTrackNumber.Enabled = true;
                    if (txtTrackNumber.EditValue != null)
                    {
                        txtTrackNumber.EditValue = null;
                    }

                    DevExpress.XtraEditors.DXErrorProvider.ConditionValidationRule conditionValidationRule = new DevExpress.XtraEditors.DXErrorProvider.ConditionValidationRule();
                    conditionValidationRule.ConditionOperator = DevExpress.XtraEditors.DXErrorProvider.ConditionOperator.IsNotBlank;
                    conditionValidationRule.ErrorText         = "Select Tracking Number ...";
                    conditionValidationRule.ErrorType         = DevExpress.XtraEditors.DXErrorProvider.ErrorType.Critical;
                    ValidationProvider.SetValidationRule(txtTrackNumber, conditionValidationRule);
                }
            }
            catch (Exception ex)
            {
                if (CDS.Shared.Exception.UserInterfaceExceptionHandler.HandleException(ref ex))
                {
                    throw ex;
                }
            }
        }