Is your search using a "POST" method? Does the search itself work? It looks like it is implemented into your query with $_GET.
Try changing your insert to:
<?php
if (isset($_GET["zoom_query"])) {
$InsertQuery = new WA_MySQLi_Query($web_catalogues_i);
$InsertQuery->Action = "insert";
$InsertQuery->Table = "searchphrases";
$InsertQuery->bindColumn("searchphrase", "s", "".((isset($_GET["zoom_query"]))?$_GET["zoom_query"]:"") ."", "WA_DEFAULT");
$InsertQuery->saveInSession("");
$InsertQuery->execute();
$InsertGoTo = "";
if (function_exists("rel2abs")) $InsertGoTo = $InsertGoTo?rel2abs($InsertGoTo,dirname(__FILE__)):"";
$InsertQuery->redirect($InsertGoTo);
}
?>