private void FillData()
        {
            PressureLossReportHelper helper = PressureLossReportHelper.instance;

            if (helper == null)
            {
                return;
            }

            if (helper.Domain == ReportResource.ductDomain)
            {
                filterCategories.Add(Autodesk.Revit.DB.BuiltInCategory.OST_DuctSystem);
                this.Text = ReportResource.ductSystemSelectorDlgTitle;
            }
            else if (helper.Domain == ReportResource.pipeDomain)
            {
                filterCategories.Add(Autodesk.Revit.DB.BuiltInCategory.OST_PipingSystem);
                this.Text = ReportResource.pipeSystemSelectorDlgTitle;
            }

            //default add all valid system type to checked system type
            foreach (Autodesk.Revit.DB.BuiltInCategory categoryId in filterCategories)
            {
                ICollection <Autodesk.Revit.DB.Element> founds = helper.getCategoryTypeElements(categoryId);
                foreach (Autodesk.Revit.DB.MEPSystemType sysType in founds)
                {
                    if (helper.isValidSystemType(sysType))
                    {
                        allValidSystemType.Add(sysType);
                    }
                }
            }

            checkedSystemType = helper.getSelectedSystemTypes();
            if (checkedSystemType == null || checkedSystemType.Count < 1)
            {
                if (checkedSystemType == null)
                {
                    checkedSystemType = new List <MEPSystemType>();
                }
                foreach (Autodesk.Revit.DB.MEPSystemType sysType in allValidSystemType)
                {
                    checkedSystemType.Add(sysType);
                }
            }

            //sort the system types
            SortSystemTypeByNameCamparer systemTypeCompare = new SortSystemTypeByNameCamparer();

            checkedSystemType.Sort(systemTypeCompare);
            allValidSystemType.Sort(systemTypeCompare);


            foreach (Autodesk.Revit.DB.BuiltInCategory categoryId in filterCategories)
            {
                ICollection <Autodesk.Revit.DB.Element> founds = helper.getCategoryElements(categoryId);
                addItemsToCheckList(helper, founds);
            }
        }