bug? processing multi selects

Anon

i have an interesting problem where queries are being executed, but the changes are not reflected in the database.

i have a multi select that is used for re-ordering content items in a cms application. after moving the content items around in a multi select using javascript, the user submits the form.

the following javascript executes on submit to grab the multi select array:

<pre>
function selectAllSubmit(formElement) {
for (i=0; i < document.fm[formElement].options.length; i++) {
document.fm[formElement].options.selected = true;
document.fm.submit();
}
}

</pre>


then, the template loops through the form array, updating the sequence of the items in the database.

<pre>

process the select list and update content_element

for ($i = 1; $i <= sizeof($elementArray); $i++) {

	$iMinusOne = $i -1;

	$query = "update content_element set sequence=$i where contentElementID = $elementArray[$iMinusOne]";

	$dbSequenceUpdate = mysql_query($query);

	print("$query<br>mysql_affected_rows: ".mysql_affected_rows()."<br>");



}

</pre>

the print statements you see are for my own sanity as i debug, and they tell me that the correct update statements are being executed. 
however, when i go directly to the database and check the data, on seemingly random occasions, the item that i moved in the multi select did not get the sequence number it should of.

a call to phpinfo() confirms that the form array is making it to the processing template as it should.

thanks in advance, 
ed