confirm box in php

Hallo allemaal.
Ik krijg de confirm box maar niet aan de praat in mijn scriptje.
wie weet raad?

<?php
while($record = mysqli_fetch_assoc($myData)){
echo "<form action=updatevriend.php method=post onclick=return confirm('Weet u het zeker?')>";
echo "<tr>";
echo "<td>" . "<input type=text name=Id value=" . $record['Id'] . " </td>";
echo "<td>" . "<input type=text name=Voornaam value=" . $record['Voornaam'] . " </td>";
echo "<td>" . "<input type=text name=Achternaam value=" . $record['Achternaam'] . " </td>";
echo "<td>" . "<input type=text name=Adres value=" . $record['Adres'] . " </td>";
echo "<td>" . "<input type=text name=Woonplaats value=" . $record['Woonplaats'] . " </td>";
echo "<td>" . "<input type=text name=GSM value=" . $record['GSM'] . " </td>";
echo "<td>" . "<textarea type=text cols='20' name=Omschrijving rows='5' value=>" . $record['Omschrijving'] . " </textarea></td>";
//echo "<td>" . "<input type=hidden name=hidden value=" . $record['Id'] . " </td>";
echo "<td>" . "<input type=submit name=update value=update>" . "</td>";
echo "<td>" . "<input type=submit name=del value=verwijder>" . "</td>";
echo "</tr>";
echo "</form>";
}
?>