kontakt mellem .html og .php

Hvorfor virker det ikke?

PHP KODE:"do_calculate.php"

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<TITLE>- Bønne tæller resultat</TITLE>
<meta name="Generator" content="Stone's WebWriter 4">
</HEAD>
<BODY>
<?php

$pris = 0;
$antal = 0;
$moms = .25;
$moms_pct = $moms * 100;
$subtotal = $pris * $antal;
$moms_pris = $subtotal * $moms;
$total = $subtotal + $moms_pris;

$fmt_pris = sprintf("%0.2f",$pris);
$fmt_subtotal = sprintf("%0.2f",$subtotal);
$fmt_moms_pris = sprintf("%0.2f",$moms_pris);
$fmt_total = sprintf("%0.2f",$total);
   
?>
<table width="200">
<tr>
<td><?php echo "<p>Antal poser kaffe bestilt :</p>" ?></td>
<td align="right">
<?php echo "<p>$antal Stk.</p>\n"; ?></td>
</tr>
<tr>
<td><?php echo "<p>Én pose kaffe koster :</p>" ?></td>
<td align="right">
<?php echo "<p>$fmt_pris Kr.</p>"; ?></td>
</tr>
<tr>
<td><?php echo "<p>Subtotal :</p>" ?></td>
<td align="right">
<?php echo "<p>$fmt_subtotal Kr.</p>"; ?></td>
</tr>
<tr>
<td><?php echo "<p>Moms ($moms_pct%) :</p>" ?></td>
<td align="right">
<?php echo "<p>$fmt_moms_pris Kr.</p>"; ?></td>
</tr>
<tr>
<td><?php echo "<p>At betale :</p>" ?></td>
<td align="right">
<?php echo "<p>$fmt_total Kr.</p>"; ?></td>
</tr>
<?php
?>
</BODY>
</HTML>


HTML KODE:"show_calculate.html"

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>- Bønne tæller form</title>
<meta name="Generator" content="Stone's WebWriter 4">
<meta name="Author" content="ZebZone.dk" />
</head>
<body>
<form method="post" action="do_calculate.php">
<table>
<tr>
<p><td>Pris for én pose kaffe :&nbsp;</td>
<td><input type="text" name="pris" size="10" maxlength="10"></td></p>
</tr>
<tr>
<p><td>Antal poser :&nbsp;</td>
<td><input type="text" name="antal" size="10" maxlength="10"></td></p>
</tr>
<tr>
<p><td><input type="submit" value="OK"></td></p>
</tr>
</table>
</form>
</body>
</html>