wrong image showing in image modal

Question

i'm working in application in php, that gets all files in a folder, and list the files in a table likes this

<?php
    // open this directory 
    $myDirectory=opendir("./server/".$_SESSION['username']."/".$_SESSION['nomepc']."/Tasklist/");

        $mdir = "server/".$_SESSION['username']."/".$_SESSION['nomepc']."/Tasklist/";
        while($entryName = readdir($myDirectory)) {
         $dirArray[] = $entryName;
       }


       closedir($myDirectory);


       $indexCount  = count($dirArray);
       Print (intval($indexCount)-2 ." Imagens <center><a href='downloadsFicheiros/downloadTasklist.php'>Fazer downloads Tasklist</a></center>");

       sort($dirArray);
       print("<TABLE class=table>\n");
       print("<TR><TH>Filename</TH><th>Eliminar<button onclick='confirmaApaga()'>Apagar tudo</button></th><th>Ficheiro Criado em</th></TR>\n");

       for($index=0; $index < $indexCount; $index++) {
        $tiraExt = preg_replace('/\\.[^.\\s]{3,4}$/', '', $dirArray[$index]);
        $str = str_replace("foto_", "", $tiraExt);


        if (substr("$dirArray[$index]", 0, 1) != "."){ 
          echo('<TR><TD><a data-toggle="modal" data-target=".bs-example-modal-sm"><img height="80" width="120" src="img/txtFile.png"</a></td>');
          print("<td>");
          echo('<a href="apagarFicheiros/tasklist/apagarFicheiroTasklist.php?ficheiro='.$dirArray[$index].'"><button class="btn btn-danger"> Apagar Ficheiro</button></a>');
          print("</td>");
          print("<td>");
         $filename = "$mdir/$dirArray[$index]";

         if (file_exists($filename)) {
            echo date ("d F Y H:i:s.", filemtime($filename));
          }
          print("</td>");
          print("</TR>\n");
        }
     }
print("</table>\n");
?>

this show us a table with the files inside the folder. now, i create a div modal in bootstrap and i call the modal in table

div bootstrap

<div class="modal fade bs-example-modal-sm" tabindex="-1" role="dialog" aria-labelledby="mySmallModalLabel">
          <div class="modal-dialog modal-sm" role="document">
              <div class="modal-content">
                  <?=print( "<img height='480' width='720' src='$filename'")?> </div>
          </div>
  </div>

call the modal in php

echo('<TR><TD><a data-toggle="modal" data-target=".bs-example-modal-sm"><img height="80" width="120" src="img/txtFile.png"</a></td>');

and when I click in the txtFile.png shows the modal but instead of showing the right image its shows the last image of the table.