Why won't this work?

[Aros]

I'm trying to collapse a non-standard form (I coded myself) but it won't collapse, here's the code;

<table width="100%" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td width="1" height="38"><img src="{if}/side_head-lr.gif" alt="" border="0" /></td>
<td width="100%" height="38" style="background-image: url({if}/side_head-bg.gif)"><div style="float: left" class="sidebox">Text</div><div style="float: right"><a href="#top" onclick="return toggle_collapse(sidebox_1')"><img id="collapseimg_sidebox_1" src="$stylevar[imgdir_button]/collapse_tcat{$collapseimg_forumid}.gif" alt="" border="0" /></a></div></td>
<td width="1" height="38"><img src="{if}/side_head-lr.gif" alt="" border="0" /></td>
</tr>
</tbody>
</table>

<table class="tborder2" cellpadding="0" cellspacing="1" border="0" width="100%" align="center">
<tbody id="collapseobj_sidebox_1" style="{$collapseobj_forumid}">
<tr>
<td class="sbc">Text</td>
</tr>
</tbody>
</table>

As you can see I've defined everything, why doesn't it work?