vbscript客户端取SELECT控件的值出错

[salangane0954]

用以下方式，取得size = 8 的select控件的值出错，但是我看不出错在了那里
selCounterID为select控件的名称

intIndex = -2
intIndex=document.form1.selCounterID.selectedIndex
strCounterID = document.form1.selCounterID.options(intIndex).value
strCheck = strCheck & strCounterID

[lzp4881]

<script language="vbscript">
function showValue()
intIndex = -2
intIndex=document.form1.selCounterID.selectedIndex
strCounterID = document.form1.selCounterID.options(intIndex).value
strCheck = strCheck & strCounterID
msgbox(strCheck)
end function
</script>

<FORM METHOD="POST" name="form1" ACTION="mtable.asp">
<select name="selCounterID" onChange="showValue()">
<option value="zv01">zv01</option>
<option value="zv02">zv02</option>
<option value="zv03">zv03</option>
</select>
</form>

[salangane0954]

有没有人知道的啊？