Problème en php

Bonjour,
J'ai une page .php
les sélects sont remplient a l'aide de la base de donner MySQL et s'affiche normale.
mais la page n'exécute pas le fichier JavaScript qui permet le calcul.
Voici le code:
<HTML>
<head>
<script type="text/javascript" src="calcule.js"> </script>
</head>
<BODY background="fond2.jpg">
<?php
$host="localhost";
$user="root";
$pass="";
$name="bp";
mysql_connect ($host,$user,$pass) or die ("erreur de connexion");
mysql_select_db($name) or die (mysql_error());
?>
<div style="position: absolute; z-index: 1; left: 250px; top: 20px" id="couche1">
<form name="f2" method='POST' onSubmit="return calcule()">
<table align="left" Border="4" bgcolor="#96D7F5" bordercolorlight="#0000FF" >
<tr > <td colspan="3"> <center> <H2> <strong>Calcul Bande Passante (VoIP)</strong></H2> </center> </td> </tr>
<TR><TD><center>Taille</center></TD> <TD colspan="2" > <center> <Select name="taille" > <option> Taille de l'echantillon </option> <option value="5"> 5 </option><option value="10"> 10 </option> <option value="20"> 20 </option> <option value="30"> 30 </option> <option value="40"> 40 </option> </select> ms </center> </TD></TR>
<TR><TD > <center> Codec </center></TD> <TD> <center> <SELECT name="Codec" id="Codec"> <option> Codec </option> <option value="8"> G.711 </option> <option value="1"> G.729 </option>
<?php
$sql = 'SELECT * FROM 'Codec'';
$SqlStr = mysql_query($sql);
while ($rang=mysql_fetch_array($SqlStr))
{
$nom = $rang['Nom'];
$mos= $rang['mos'];
$coif= $rang['coif'];
$deb=$mos*$coif;
echo "<option value='$deb'> $nom </option>";
}
?>
</select> </center> </TD> </TR>
<TR><TD > <center> Mos</center></TD> <TD colspan="2" ><center><input type="text" name="mos" value="" /> </center></TD></TR>
<tr><center> <TD colspan="3" > <center> <a href="AjoutCodec.html"> <input type="button" value="Ajouter Codec" onClick="AjoutCodec.html" /> </a> </center> </TD> </center></tr>
<TR> <TD ><center>IP</center></TD> <TD colspan="2" ><center> <input type="radio" name="s" value="20" checked> IPv4 <input type="radio" name="s" value="40"> IPv6 </center></TD></tr>
<TR> <TD ><center> VAD</center></TD><td colspan="2" > <center><input type="text" value="0.7" name="vad"/> </center></TD></tr>
<TR> <td > <center> Protocole L2 </center></td><TD colspan="2" > <center> <Select name="pl2" ><option value="18"> Ethernet Half </option> <option value="22"> Ethernet Half avec Priorite </option> <option value="28"> Ethernet Full </option> <option value="32"> Ethernet Full avec Priorite </option> <option value="8"> PPP</option> <option value="6"> Frame Relay </option></Select> </center></TD></TR>
<tr><center> <TD colspan="3" > <center> <a href="AjoutProtocole.html"> <input type="button" value="Ajouter Protocole Couche 2" onClick="AjoutCodec.html" /> </a> </center> </TD> </center></tr>
<TR> <TD colspan="3"><center> <input type="Submit" value="Calculer" /> <input type="Reset" value="Annuler" /> </center> </TD></TR>
<TR > <TD colspan="3"> <center> <H3> Pour un appel </H3></center> </TD></TR>
<TR > <td > <center> Bande Passante L3</center></td><TD colspan="2" ><input type="Text" name="l3" /> kb/s</TD></TR>
<TR> <td> <center> Bande Passante L2 </center></td><TD colspan="2" ><input type="Text" name="l2" />kb/s </TD></TR>
<TR> <td colspan="3"> <center> <H3> Pour N appels </H3></center> </td></TR>
<TR> <td ><center> N </center></td> <td colspan="2" ><input type="text" name="n" /> </TD></TR>
<TR > <TD colspan="3"><center> <input type="button" value="ReCalculer" onClick="recalcule()" /> </center></TD></TR>
<TR> <td ><center> Bande Passante L3 </center></td><TD colspan="2" > <input type="Text" name="nl3"/> kb/s </TD></TR>
<TR> <td ><center> Bande Passante L2 </center></td><TD colspan="2" > <input type="Text" name="nl2" /> kb/s </TD></TR>
</table>
</form>
</div>
</BODY>
</HTML>

calcule.js
// JavaScript Document
function calcule()
{
//calcule

//declaration des variables & initialisation

var taille=parseInt(document.f2.taille.value);
var codec=parseInt(document.f2.codec.value);
if(document.f2.s[0].checked)
id=20;
if(document.f2.s[1].checked)
id=40;
if(!(document.f2.s[0].checked)&&!(document.f2.s[1].checked))
{
alert("vous devez choisir un ID");document.f2.focus();return false;}
var vad=document.f2.vad.value;
var pl2=document.f2.pl2.value;
//verification

if(isFinite(taille)==false)
{alert("verifier la taille");
document.f2.taille.focus();return false;
}

if(isFinite(codec)==false)
{alert("Verifier le Codec");
document.f2.codec.focus();return false;
}

if(document.f2.codec.selectedIndex+1==8){
var vad=1;
document.f2.codec.focus(); return false;
}
var a=codec*taille;
var a1=a+id+20;
var a2=1000/taille;
var a3=a1*a2;
var a4=a3*vad;
var a5=a4*8;
var a6=a5/1000;

document.f2.l3.value=(a6);
document.f2.l3.focus();

if(document.f2.codec.selectedIndex+1==8){
var vad=1;
}
var b=codec*taille;
var b1=b+id+20+parseInt(pl2);
var b2=1000/taille;
var b3=b1*b2;
var b4=b3*vad;
var b5=b4*8;
var b6=b5/1000;

document.f2.l2.value=(b6);
document.f2.l2.focus(); return false;
}

function recalcule()
{
var n=parseInt(document.f2.n.value);
if (isNaN(n)) {
alert("n est un nombre");
}
var r=(document.f2.l2.value);
var r1=(document.f2.l3.value);
var c=(n*r);

var c1=(n*r1);

document.f2.nl3.value=(c1);
document.f2.nl2.value=(c);
document.f2.nl2.focus(); return false;

}