用iframe 调用form 出错，不知道如何调用才能成功啊

Question

<iframe name="iframe_data" style="display:none;"></iframe>
<form name="downLoad" id="downLoad" method="post" action="[!--downpath--]" target="iframe_data">
<script> document.download.submit();</script>
                                        <table border="0" cellpadding="0" cellspacing="0" background="/skin/3gsp/image/gx_ljxz.gif" class="hand mb7" onclick="javascript:if(0 >0)if(!confirm('下载该资料将扣除0分，是否继续？'))return false;document.downLoad.submit();">
<tr>                                                        
<td width="184" height="37" align="right"><span class="f10">[!--userfen--]分<br>[!--filesize--]</span></td>
        <td width="7"></td>
        </tr></form>