Problem with Sort by "Created" and "Duedate"

[Misha]

Hi, I got into one problem. I learned from site how add sortable links into ostickets. Thanks God all it works. There is only problem that sorting by date doesn't work correctly. It kind of sorting but on its own way that has no sense.

Here is the code that I changed in ticket.inc.php
Any help would be greatly appreciated.

PHP Code:

184. $sortOptions=array('date'=>'ticket.created','ID'=> 'ticketID','pri'=>'priority_urgency','dept'=>'dept _name','duedate'=>'duedate','ass'=>'username','timeopen'=>'ticket.lastresponse','from'=>'name','created'=>'created', 'waiting'=>'dept_id','subject'=>'subject');
$orderWays=array('DESC'=>'DESC','ASC'=>'ASC'); 


PHP Code:

394. <th width="70" >
                <a href="tickets.php?sort=ID&order=<?=$negorder?><?=$qstr?>" title="Sort By Ticket ID <?=$negorder?>">Ticket</a></th>
            <!--th width="70">
                <a href="tickets.php?sort=date&order=<?=$negorder?><?=$qstr?>" title="Sort By Date <?=$negorder?>">Date</a></th-->
        <th width="115">
                <a href="tickets.php?sort=timeopen&order=<?=$negorder?><?=$qstr?>" title="Sort By Age <?=$negorder?>">Last Response</a></th>
            <th><a href="tickets.php?sort=subject&order=<?=$negorder?><?=$qstr?>" title="Sort By Subject <?=$negorder?>">Subject</th>
            <!--th width="120">
                <a href="tickets.php?sort=dept&order=<?=$negorder?><?=$qstr?>" title="Sort By Category <?=$negorder?>">Department</a></th-->
            <th width="80" ><a href="tickets.php?sort=ass&order=<?=$negorder?><?=$qstr?>" title="Sort By Assignee <?=$negorder?>">Assigned To</a></th>
            <th width="80">Waiting On</th>
        <th nowrap><a href="tickets.php?sort=duedate&order=<?=$negorder?><?=$qstr?>" title="Sort By Due Date <?=$negorder?>">Due Date</a></th>
            <th width="115"><a href="tickets.php?sort=created&order=<?=$negorder?><?=$qstr?>" title="Sort By Creted <?=$negorder?>">Created</a></th>
        <th width="70">
                <a href="tickets.php?sort=pri&order=<?=$negorder?><?=$qstr?>" title="Sort By Priority <?=$negorder?>">Priority</a></th>
            <th width="180" ><a href="tickets.php?sort=from&order=<?=$negorder?><?=$qstr?>" title="Sort By From <?=$negorder?>">From</a></th> 
        </tr>