上移下移 没有效果 jQuery

Question

<script src="_scripts/jquery-1.3.2.min.js" type="text/javascript"></script>
<script type="text/javascript">
         function MoveDown() {
             var selectedOption = $('#ListBox1 > option[selected]');
             var nextOption = $('#ListBox1 > option[selected]').next("option");            
             if ($(nextOption).text() != "") {              
                 $(selectedOption).remove();
                 $(nextOption).after($(selectedOption));
             }                 
         }
         function MoveUp() {
             var selectedOption = $('#ListBox1>option[selected]');
             var prevOption = $('#ListBox1>option[selected]').prev("option");             
             if ($(prevOption).text() != "") {
                 $(selectedOption).remove();
                 $(prevOption).before($(selectedOption));
             }
           }
     </script>  

Answer 1

function UpOrDownOption(Sel,direction)
{
   var Op=Sel.options;
   var selectedNub=0;
   for(var i=0;i<Op.length;i++)
   {
      if(Op[i].selected)
      {
         selectedNub++;
      }
   }
   if(selectedNub==0)
   {
      alert("请选择一项！");
      return;
   }
   if(selectedNub>1)
   {
      alert("只能选择一项！");
      return;
   }
   i=Sel.selectedIndex;
   var selectedOp=document.createElement("option");
      selectedOp.text=Op[i].text;
      selectedOp.value=Op[i].value;
      selectedOp.selected=true;
      
      if(direction=="up")
      {
      if(i!=0)
   {
      Sel.options.add(selectedOp,i-1);
         Sel.options.remove(i+1);
   }
         
      }
      if(direction=="down")
      {
      if(i!=Op.length-1)
      {
         Sel.options.add(selectedOp,i+2);
         Sel.options.remove(i);
         }
      }
   
}