Indtastede oplysninger ryger ikke ind i databasen!

Hej Alle
Jeg har et problem jeg ikke kan løse. Håber der er en, der kan hjælpe!
Problemet er det, at alt tilsyneladene ser fint ud. Når man har udfyldt alt og afsender oplysningerne til databasen
kommer der ingen fejlmeldinger og alt ser ud til at være sendt! men intet er havnet i databasen. Hvad mangler der?
Tak!
php dokument ser således ud:

<?
    $dbhost = "noget.dk";
    $database = "xx";
    $dbuser = "xxx";
    $dbpass = "xxx";

    mysql_connect($dbhost,$dbuser,$dbpass);
    mysql_select_db($database);
?>
<?
if ($_POST[action] == "update"){
    $dlg = ($_POST[dlg]);
    $navn = ($_POST[navn]);
    $bem = ($_POST[bem]);
    $produkt = ($_POST[produkt]);
    $telefon = ($_POST[telefon]);
    $adresse = ($_POST[adresse]);
    $postnr = ($_POST[postnr]);
    $by = ($_POST[by]);

    mysql_query("INSERT INTO dsl SET navn = '$navn',dlg = '$dlg',bem = '$bem',telefon = '$telefon',produkt = '$produkt',adresse = '$adresse',dlg = '$dlg',by = '$by',postnr = '$postnr',");
}
?>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<a href="tilfoej.php"><img border="0" src="1.gif"><a>&nbsp;&nbsp;&nbsp;&nbsp;<a href="soeg.php"><img border="0" src="2.gif"><a>
<?
if ($m == "saadan") {
?><br>
<font color="red" size="4" face="verdana">
Kunden er Tilføjet...
<?
}
?>
<form action=tilfoej.php?m=saadan method=post>
<input type="hidden" name="action" value="update">
  <table border="0" width="493" height="1" cellspacing="0" cellpadding="0">
    <tr>
      <td height="24" colspan="2"> <p align="center"><font size="2" face="Verdana">Tilføj
          kunden til databasen</font></td>
    </tr>
    <tr>
      <td width="109" height="13"> <p align="center"><font size="2" face="Verdana">DLG
          : </font></td>
      <td width="221" height="13"> <font size="2" face="Verdana">
        <input name="dlg" type="text" style="background-color: #FFFFFF; color: #000000; font-size: 13 px; font-family: Verdana; font-weight: bold; border: 1 solid #000000" size="5" maxlength="6">
        </font></td>
    </tr>
    <tr>
      <td width="109" height="13"> <p align="center"><font size="2" face="Verdana">Navn
          :</font></td>
      <td width="221" height="13"> <font size="2" face="Verdana">
        <input type="text" name="navn" size="20" style="background-color: #FFFFFF; color: #000000; font-size: 13 px; font-family: Verdana; font-weight: bold; border: 1 solid #000000">
        </font></td>
    </tr>
    <tr>
      <td width="109" height="4"><p align="center"><font size="2" face="Verdana"> Adresse :</font></td>
      <td width="221" height="4"><font size="2" face="Verdana">
        <input name="adresse" type="text" style="background-color: #FFFFFF; color: #000000; font-size: 13 px; font-family: Verdana; font-weight: bold; border: 1 solid #000000" value="" size="20">
        </font></td>
    </tr>
    <tr>
      <td width="109" height="4"><p align="center"><font size="2" face="Verdana">Postnr.By</font></td>
      <td width="221" height="4"><font size="2" face="Verdana">
        <input name="postnr" type="text" style="background-color: #FFFFFF; color: #000000; font-size: 13 px; font-family: Verdana; font-weight: bold; border: 1 solid #000000" value="" size="5" maxlength="4">
        <input type="text" name="by" size="20" style="background-color: #FFFFFF; color: #000000; font-size: 13 px; font-family: Verdana; font-weight: bold; border: 1 solid #000000">
        </font></td>
    </tr>
    <tr>
      <td width="109" height="13"> <p align="center"><font size="2" face="Verdana">Telefon :
          :</font></td>
      <td width="221" height="13"> <font size="2" face="Verdana">
        <input name="telefon" type="text" style="background-color: #FFFFFF; color: #000000; font-size: 13 px; font-family: Verdana; font-weight: bold; border: 1 solid #000000" size="20" maxlength="13">
        </font></td>
    </tr>
    <tr>
      <td width="109" height="9"> <p align="center"><font size="2" face="Verdana">Produkt
          :</font></td>
      <td width="221" height="9"><font size="2" face="Verdana">
        <select size="1" name="katekori" style="font-size: 13 px; font-family: Verdana; background-color: #FFFFFF; color: #000000">
          <option selected>Vælg Produkt :</option>
         
        </select>
        </font></td>
    </tr>
    <tr>
      <td width="109" height="3"> <p align="center">Bem&aelig;rkninger : </td>
      <font size="2" face="Verdana"></font></td><font size="2" face="Verdana">&nbsp;
      </font>
      <td width="163" height="3"><font size="2" face="Verdana">
        <textarea rows="2" name="bes" cols="20" style="background-color: #FFFFFF; color: #000000; font-size: 13 px; font-family: Verdana; font-weight: bold; border: 1 solid #000000"></textarea>
        </font></td>
    </tr>
    <tr>
      <td width="109" height="1"> <p align="center"><font size="2" face="Verdana"><br>
          Udfør</font></td>
      <td width="221" height="1"><font size="2" face="Verdana"><br>
        <input type="submit" name="update" value="Tilføj" style="background-color: #FFFFFF; color: #000000; font-size: 13 px; font-family: Verdana; font-weight: bold; border: 1 solid #000000">
        </font></td>
    </tr>
  </table>
</form>