spring mvc note able to display my page

I am having problem when displaying new page from controller. Here when i return modelandview object it come to login page(login.jsp) but when i return string it display correct page(admin.jsp).

Returning ModelAndView..

    if (bean.getUserName().equalsIgnoreCase("rohit") && bean.getPassWord().equalsIgnoreCase("rawat"))
    {
        AdminHomeBean admin = new AdminHomeBean();
        return new ModelAndView("admin/admin", "adminHbean", admin);
    }
    else
    {
        bean.setErrorMsg("User Name or Password is Incorret");
        return new ModelAndView("login/login", "loginbean",bean); 
    }

This method always returns the login page.

Return String..

return "admin/admin";

This works fine. and return admin page.

Please help..