<input type="radio" name="ddir"  onCLICK="" value="<?=$r->sys_pk ?>" id="dir<?=$r->sys_pk ?>" /></td> 

<td class="black2">Benutzer und Rechte:</td>
 <?php
 $query = "SELECT u.name FROM t_user u INNER JOIN tr_directories_user r ON r.fk_t_user=u.sys_pk WHERE r.fk_t_directories=".$r->sys_pk;//some wrong in assigning this 
 $result = mysql_query($query) or die("Query failed : " . mysql_error());
   while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
  print "\t<tr>\n";
  foreach ($line as $col_value) {
      print "\t\t<td class='black2'>$col_value</td>";
                                                  }
                    print "\t</tr>\n";
              }

   ?>