轻微如何样判断html:multibox不能为空

轻微怎么样判断html:multibox不能为空？
<html:multibox   property= "search_popedom.check_pope "   value= "1 "   /> a  
<html:multibox   property= "search_popedom.check_pope "   value= "2 "   /> b  
<html:multibox   property= "search_popedom.check_pope "   value= "3 "   /> c
<html:multibox   property= "search_popedom.check_pope "   value= "4 "   /> d  
<html:multibox   property= "search_popedom.check_pope "   value= "5 "   /> e  
<html:multibox   property= "search_popedom.check_pope "   value= "6 "   /> f

<html:form   action= "pope.do? "   onsubmit= "return   check() ">

  function   check(){
                      alert(document.forms[0].search_popedom.check_pope.value);            
  }
为什么获取不到html:multibox的值，
我写成这样也不对
document.all[ 'search_popedom.check_pope '].value;
请问是什么原因？

------解决方案--------------------
function checkbl(){
var list=document.getElementsByName( "search_popedom.check_pope ");
var bl=0;
for(var i=0;i <list.length;i++){
if(document.getElementsByName( "search_popedom.check_pope ")[i].checked){
bl++;
}
}
return bl==0;
}
然后再提交时调
function check(){
if(checkbl()){
alert( "不能为空 ");
}
}
------解决方案--------------------
var boxe1 = document.getElementsByName( "checkCountry ");

var check1 = new Array();
for (var i = 0; i < boxe1.length; i++)
{
if (boxe1[i].checked)
{
check1[check1.length] = boxe1[i].value;
}
}
if(check1.length <1)
{
alert( "请选择一个country！ ");
return false;

这是得到所有选中的值，自己改改应该可以的