Using jscript to click type=file button

Hi, I'm trying to make a page with HTML, PHP and JS wich should realise a file upload. The code i'm using is shown below :

<code>
<script type="text/javascript">
function getfile(){
document.getElementById('hiddenfile').click();
document.getElementById('selectedfile').value=document.getElementById('hiddenfile').value
}
</script>

<FORM ACTION="<?php echo(BASENAME($_SERVER['PHP_SELF']))?>" METHOD=POST enctype=multipart/form-data NAME=general>
<TR><TD>
<input type="file" id="hiddenfile" name="hiddenfile" value="<?echo $_POST['hiddenfile'];?>"/>
<input type="text" id="selectedfile" value="<?echo $_POST['selectedfile'];?>"/>
<input type="button" value="Select a file" onclick="getfile()" />
<input type="submit" value="Verstuur"/>
</TR</TD>
</code>

The problem is that the submit clears the field with name="hiddenfile" on the moment (before, i believe) the upload must be realised, so there is no upload no filled $_FILES. Who can tell me what i'm doing wrong ?

Greets Frans