part of the problem is that you are trying to pass querystring variables along in the forms action;
<form action="search_results2.php?SiteID=<?php echo $row_rsTopPic['SiteID']; ?>&lang=<?php echo $row_rsTopPic['Lang_abr']; ?>" method="get" name="WADASearchForm" id="WADASearchForm">
when you use the get method to send the form information, it will overwrite any existing querystring varables.
in other words, using the get method will strip any querystring variables you try to include in the forms action and replace them with the form data.
to send any information on form submit through the querystring when using the get method, it must be part of the form.
add 2 hidden form elements to the search form to send the querystring info :
<input name="SiteID" type="hidden" id="SiteID" value="<?php echo $row_rsTopPic['SiteID']; ?>" />
<input name="lang" type="hidden" id="lang" value="<?php echo $row_rsTopPic['Lang_abr']; ?>" />
if you're styill having problems, the next step is to write the query being executed to the screen, add the following code after the body tag:
<?php echo"SQL: ".$query_limit_WADApages."<br />"); ?>
and post back the query.