一个修改页面的问题

添加页面的代码：
<tr>
    <td height="24" align="right">推荐等级</td>
    <td><span style="border-left: 1px solid #D4D0C8; border-right: 1px solid #D4D0C8; border-top: 1px solid #D4D0C8; padding: 0">
      <select name="Down_Level" id="Down_Level" onChange="changelevel(this)">
        <option value="level1">1</option>
        <option value="level2">2</option>
        <option value="level3" selected="selected">3</option>
        <option value="level4">4</option>
        <option value="level5">5</option>
      </select>
      <img src="../sys_images/level3.gif" name="Lshow" align='absmiddle' id="Lshow" />
      <script>
    function changeweather(obj){
      document.all.wshow.src="../sys_images/weather/hn2_" + obj.value + ".gif"
    }
    function changelevel(obj){
      document.all.Lshow.src="../sys_images/" + obj.value + ".gif"
    }
      </script>
    </span></td>
  </tr>
修改页面的代码：
    <tr>
    <td height="24" align="right">推荐等级</td>
    <td>
    <span style="border-left: 1px solid #D4D0C8; border-right: 1px solid #D4D0C8; border-top: 1px solid #D4D0C8; padding: 0">
    <%
    Call DBConnBegin()
    Sql="select * from down Where Down_ID="&Request("ID")
    oRs.open Sql,oConn,1,1
    %>
    <select name="Down_level" id="Down_level">
      <option value="level1"<%if oRs("Down_Level")="level1" then Response.Write(" selected")%>>1</option>
      <option value="level2"<%if oRs("Down_Level")="level2" then Response.Write(" selected")%>>2</option>
      <option value="level3"<%if oRs("Down_Level")="level3" then Response.Write(" selected")%>>3</option>
      <option value="level4"<%if oRs("Down_Level")="level4" then Response.Write(" selected")%>>4</option>
      <option value="level5"<%if oRs("Down_Level")="level5" then Response.Write(" selected")%>>5</option>
    </select>
      <img src="../sys_images/<%=oRs("Down_Level")%>.gif" name="Lshow" align='absmiddle' id="Lshow" />
      <%Call DBConnEnd()%>
      <script>
    function changeweather(obj){
      document.all.wshow.src="../sys_images/weather/hn2_" + obj.value + ".gif"
    }
    function changelevel(obj){
      document.all.Lshow.src="../sys_images/" + obj.value + ".gif"
    }
      </script>
    </span>
    </td>
  </tr>
添加页面中选择不同等级，后面的等级图片也会随之变化。
而修改页面中在选择不同的等级，后面的等级图片就不变了，怎么修改呢？