Object doesn't support this property or method

Object doesn't support this property or method

I need a little help guys.
 
  1. function FindSelectedType(){
     var objChecked = null; 
     if (oneCheckBoxMode){
      objChecked = '';
      $(fields['PercentComplete']).find('input').each(function(){
       var checkbox = $(this);
       if (checkbox.attr('checked'))
        objChecked = checkbox.next().value();
      });
     }
     else{
      var objChecked = {};
      $(fields['PercentComplete']).find('input').each(function(){
       objChecked[$(this).next().value()] = $(this).attr('checked');
      });
     }
     return objChecked;
    }
















    2. It is breaking at   objChecked = checkbox.next().value();
    with "Object doesn't support this property of method". Any ideas?