toggle checkbox ved klik på span

jeg har følgende kode:

    <SCRIPT TYPE="text/javascript">
    <!--
    function togglecheck(dest, boxname) {
        if (dest.boxname.checked){
            dest.boxname.checked = true;
        } else {
            dest.boxname.checked = true;
        }
    }
    // -->
    </SCRIPT>

<form name="papers">

<table border=0 cellpadding=2 cellspacing=0>
  <tr>
    <td vAlign="top" style="padding-top: 3px;"><center><img src="arrow_dotted_yellow.gif" border="0"></center></td>
    <td><a href="downloadsignle.php" title="click here to only download this file">this is where the headline will be. Super!</a></td>
  </tr>
  <tr>
    <td vAlign="top" style="padding-top: 3px;"><center><input type="checkbox" name="box1"></center></td>
    <td style="padding-top: 3px;"><span onclick="togglecheck(this.form, 'box1');">click me to toggle the checkbox</span></td>
  </tr>
</table>

<table border=0 cellpadding=2 cellspacing=0>
  <tr>
    <td vAlign="top" style="padding-top: 3px;"><center><img src="arrow_dotted_yellow.gif" border="0"></center></td>
    <td><a href="downloadsignle.php" title="click here to only download this file">this is where the headline will be. Super!</a></td>
  </tr>
  <tr>
    <td vAlign="top" style="padding-top: 3px;"><center><input type="checkbox" name="box2"></center></td>
    <td style="padding-top: 3px;"><span onclick="togglecheck(this.form, 'box2');">click me to toggle the checkbox</span></td>
  </tr>
</table>

</form>


mit script virker ikke.

-det skal toggle den der checkbox der er ud for teksten.... hvad gør jeg forkert?