<HTML> <BODY>  <input id="dt" type=hidden name="dtrange" value="mm">
<a href="javascript:show();" target="_self">click it, succeed.</a><p>
<a href="javascript:show();" target="_blank">click it, error!</a> <script language=javascript> 
function show()
{
document.write(document.getElementsByName('dtrange')[0].value);
}
</script></BODY> 
</HTML>