document.myform.BigClassName.options' 为空或不是对象
测试的一个二级分类，上次也是用的这个程序都成功了。对照着看也看看出是哪出了问题把程序贴出来麻烦帮看一下，谢谢
网页错误详细信息
消息: 'document.myform.BigClassName.options' 为空或不是对象
行: 75
字符: 1
代码: 0
程序代码：
<form method="POST" name="myform">
<%
set rs=server.createobject("adodb.recordset")
sql = "select * from [SmallClass] "
rs.open sql,conn,1,1
%>
<script language = "JavaScript">
var onecount;
subcat = new Array();
<%
count = 0
do while not rs.eof
%>
subcat[<%=count%>] = new Array("<%= trim(rs("SmallClassName"))%>","<%= trim(rs("BigClassName"))%>","<%= trim(rs("SmallClassName"))%>");
<%
count = count + 1
rs.movenext
loop
rs.close
%>
onecount=<%=count%>;
function changelocation1(locationid)
{
document.myform.SmallClassName.length = 1;
var locationid=locationid;
var i;
for (i=0;i < onecount; i++)
{
if (subcat[i][1] == locationid)
{
document.myform.SmallClassName.options[document.myform.SmallClassName.length] = new Option(subcat[i][0], subcat[i][2]); //这是第75行
}
}
}
</script>
<table width="100%" height="32" border="0" cellpadding="0" cellspacing="1">
<tr>
<td height="30" align="left">
<%
set rs=server.createobject("adodb.recordset")
sql = "select * from [BigClass]"
rs.open sql,conn,1,1
if rs.eof and rs.bof then
response.write "请先添加栏目。"
else
%>
<select name="BigClassid" id="BigClassid" onChange="changelocation(document.myform.BigClassName.options[document.myform.BigClassid.selectedindex2].value)" size="1" >
<option selected value="<%=trim(rs("BigClassName"))%>"><%=trim(rs("BigClassName"))%></option>
<%
dim selclass
selclass=rs("BigClassName")
rs.movenext
do while not rs.eof
%>
<option value="<%=trim(rs("BigClassName"))%>"><%=trim(rs("BigClassName"))%></option>
<%
rs.movenext
loop
end if
rs.close
%>
</select>
<select name="SmallClassName" id="SmallClassName" size="1">
<option value="">不指定小类</option>
<%
set rs=server.createobject("adodb.recordset")
sql="select * from [SmallClass] where BigClassName='" & selclass & "'"
rs.open sql,conn,1,1
if not(rs.eof and rs.bof) then
%>
<option value="<%=rs("SmallClassName")%>" selected="selected"><%=rs("SmallClassName")%></option>
<% do while not rs.eof%>
<option value="<%=rs("SmallClassName")%>"><%=rs("SmallClassName")%></option>
<%
rs.movenext
loop
end if
rs.close
%>
</select>
<input name="cubname" type="text" id="cubname" size="15" />
<input type="submit" name="Submit" value="提交" />
</td>
</tr>
</table>
</form>
用浏览器，菜单：查看-查看源文件，或者网页上空白处点右键-查看源文件，把这个代码发上来。标一下75行