Spring @SessionAttributes returns null

Im trying to use @SessionAttributes in my controller class as follows:

@Controller
@SessionAttributes({"calMethods", "taxList"})
@RequestMapping("/secure")
public class reportController extends BaseController {

//..
@ModelAttribute("taxList")
    public List<multiCalDto> getTaxList() {
        return new ArrayList<multiCalDto>();
    }
//....

@RequestMapping(value = "/confirmCal.html", method = RequestMethod.GET)
    public ModelAndView launchconfirmCal(HttpServletRequest request, @RequestParam("seqNo") String seqNo) {
    ...........

    ModelAndView modelAndView = new ModelAndView("confirmCalView");
    modelAndView.addObject("taxList", calBean.getTaxList());
    return modelAndView;
      }


@RequestMapping(value = "/executeCalPay.html", method = RequestMethod.POST)
  public ModelAndView executeCalPay(HttpServletRequest request, @ModelAttribute("taxList") List<multiCalDto> taxList) {
      // ............



      ModelAndView modelAndView = new ModelAndView("calView");
      System.out.println("taxList -- "+taxList);
      return modelAndView;
    }

}

I added taxList in launchconfirmCal() and trying to access the same in executeCalPay(). I tried to print taxList before adding to modelAttribute and the size is 12 and when I retireve in executeCalPay() it shows null. I am not changing its value in JSP.