async void InitPage(PageLoader pageLoader) { OrderChallan = new Challan(); await OrderChallan.AssignChallanBookSerialNo(); PageNav = new ChallanPageNav(pageLoader, OrderChallan, this); PageSide = new ChallanPageSide(pageLoader, OrderChallan); VatList = await Tax.RetriveTaxesByType("VAT"); CstList = await Tax.RetriveTaxesByType("CST"); }