php 中js第一次取不到值

Question

1.php 文件
<form action="" name="form1" id="form1">
          <ul>
            <li><span class="buyform_s_w">Current Level:</span> <select name="levelstart" onchange="javascript:index_ckus()" id="levelstart" class="in_w">
                     <? require ("include/conn.php")?>
              <?
                       $sql_us = "select game_dj from games where id=13";
                       $arr_us = $conn -> select_array($sql_us);
                       $dj_us = $arr_us[0][0];
                     for ($i=1; $i<$dj_us; $i++)
                            {
                       ?>
                  <option value="<?=$i?>"><?=$i?></option>
              <?
                     }
                       ?>
              </select>
             <span class="buyform_s_w">Price:</span> <input name="price" type="text" id="price" disabled="disabled" class="in_w1"/>
              USD</li>
            <li></li>
            <li><span class="buyform_s_w">Desired Level:</span>&nbsp;<select name="levelend" id="levelend" onchange="javascript:index_ckus()" class="in_w">
                       
              <?
                     for($j=2;$j<=$dj_us;$j++)
                            {
                       ?>
                  <option value="<?=$j?>" <? if($i==$dj_us){echo "selected";}?>><?=$j?></option>
              <?
                     }
                       ?>
              </select>
              <span class="buyform_s_w">Time:</span> <input name="time" type="text" id="time" disabled="disabled" class="in_w1"/> 
              Hour
            </li>
            <li></li>
            <li><a href="CheckOut-WOW-US-PowerLeveling.html"><img src="img/Buy1.jpg" border="0" onmouseover="this.src='img/Buy.jpg'" onmouseout="this.src='img/Buy1.jpg'" /></a></li>
          </ul>
        </form>
<script language="javascript" src="include/javascript-http.js"></script>
<script language="javascript">index_ckus();</script>下面是JS。好像就这出错了吧。
功能都能实现，就是一打开1.php 直接点提交获取不到值。选择才行。
请朋友指点下。
var xmlhttp = false;
try{
       xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
}catch(e1){
       try{
              xmlhttp = new ActiveXObject("Mircrosoft.XMLHTTP");
       }catch(e2){
              try{
                     xmlhttp = new XMLHttpRequest();
              }catch(e3){
                     xmlhttp = false;
              }
       }
}
if(!xmlhttp){
alert('Register XMLHttp Error!');
}
function index_us(){
       if(xmlhttp.readyState==4){
              if(xmlhttp.status==200){
                     var rtxt = xmlhttp.responseText;
                            arr = rtxt.split(",");                            document.getElementById("price").value=arr[1];
                            document.getElementById("time").value=arr[2];                     //document.getElementById("a_info1").innerHTML = rtxt;
              }
       }
}
function index_ckus(){
       var game_name = 13;       var start = parseInt(document.getElementById("levelstart").value);
       var end = parseInt(document.getElementById("levelend").value);
   if(start < end){
    url = 'function.php?game_name='+game_name+'&start='+start+'&end='+end;
       xmlhttp.open('GET',url,true);
       xmlhttp.onreadystatechange = index_us;
       xmlhttp.send(null);
   }else{
        alert("Your Desired Level Must Be Greater Than Your Current Level");
              document.getElementById("levelend").focus();
   }
}
function update_name_eu(){
       if(xmlhttp.readyState==4){
              if(xmlhttp.status==200){
                     var rtxt_eu = xmlhttp.responseText;
                            arr_eu = rtxt_eu.split(",");
                                   document.getElementById("price_eu").value=arr_eu[1];
                                   document.getElementById("time_eu").value=arr_eu[2];                     //document.getElementById("a_info1").innerHTML = rtxt;
              }
       }
}
function chk_user_eu(){
       var game_name = 14;
       var start = parseInt(document.getElementById("levelstart_eu").value);
       var end = parseInt(document.getElementById("levelend_eu").value);
   if(start < end){
    url = 'function.php?game_name='+game_name+'&start='+start+'&end='+end;
       xmlhttp.open('GET',url,true);
       xmlhttp.onreadystatechange = update_name_eu;
       xmlhttp.send(null);
   }else{
        alert("Your Desired Level Must Be Greater Than Your Current Level");
              document.getElementById("levelen_eu").focus();
   }
}