[Plugin: postTabs] can’t create more than one tab set on a page

if I put this on a page:

<?php $x=0;
while($x<3): ?>
<div id=<?php echo $x; ?>>
[tab:test1]
text of tab 1
[tab:test2]
text of tab 2
[tab:END]
</div>
<?php $x++;
endwhile; ?>

I end up with a tab set of 6 tabs rather than 3 tab sets of 2 tabs each.
Additionally, <div id=”0″> contains the single tab set of 6 tabs. <div id=”1″> and <div id=”2″> contain uninterpreted shortcodes, i.e.
[tab:test1]
text of tab 1
[tab:test2]
text of tab 2
[tab:END]
appears as text not as a tab.

Does anybody have any idea why this is happening? And how to fix or at a least a big arrow in the right direction would be much appreciated.
thx.