non procude output

[wider]

$online_query = mysql_query("SELECT ipaddress,time,page FROM " . $prefix . "uonline");

        while($online_query = mysql_fetch_assoc($online_query))
        {
            if($sync != 'nosync')
                {
                    echo ',<a onMouseover="ddrivetip(\''.$online_query['ipaddress'].'\',\'yellow\', 300)"; onMouseout="hideddrivetip()">'.$online_query['username'].'</a>';
                    echo "\n";
                }
            else
                {
                    echo ',<a onMouseover="ddrivetip(\''.$online_query['page'].'\',\'yellow\', 300)"; onMouseout="hideddrivetip()">'.$online_query['ipaddress'].'</a>';
                    echo "\n";
                }    
        } 

sebbene la tabella uonline abbia 1 record all'interno, questo script non produce output (non stampa neanche il <a onMauseover.....
Perchè?
Grazie