When Check boxes are unchecked, got the error Required long[] parameter 'checked' is not present

I have the html code for check boxes

<input type="checkbox" value="4" name="checked" id="checkbox">
<input type="checkbox" value="5" name="checked" id="checkbox">
<input type="checkbox" value="6" name="checked" id="checkbox">

In Serverside

@RequestMapping(value="/add_attendance", method=RequestMethod.POST)
public ModelAndView Add_Attendance(@Valid @RequestParam("checked")long[] 
checkboxvalues,@RequestParam("atdate")String 
atdate,@RequestParam("company")String company)
{   
   ModelAndView mv=new ModelAndView();  
   atdservice.add(checkboxvalues, ChangeDateFormat.DateToDB(atdate), company);      
   mv.setViewName("admin/mark_attendance");
   mv.addObject("message",company+" attendance marked successfully!!");
   return mv;
}

It works fine when at least one check box is checked. But when all the check boxes are unchecked. I got this error