looking at the source code for the page shows an error on the user id form element:
<input type="hidden" name="user_id" value="<br />
<b>Notice</b>: Undefined variable: row_voterRecordset in <b>/home/gcssepm/www/2014election_3.php</b> on line <b>540</b><br />
" />
the user id form element is using the old mySQL binding for the value:
<input type="hidden" name="user_id" value="<?php echo $row_voterRecordset['user_id']; ?>" />
it needs to be updated to use the MySQLi binding instead