Whats wrong :S?

Ok, ive made this thing, but the update script doesnt seem to work.. it says its updated, but it hasnt..

PHP Code:

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$habbo = htmlspecialchars($_POST[habbo]);
$furni = htmlspecialchars($_POST[furni]);
$amount = htmlspecialchars($_POST[amount]);
$comment = htmlspecialchars($_POST[comment]);
$password = htmlspecialchars($_POST[password]);
$edit = mysql_query("UPDATE trade SET habbo='$habbo', furni='$furni', amount='$amount', comment='$comment', password='$password' WHERE id = '$id'");
echo("Item Updated!"); 


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Please post any suggestions :)

Theres no $id

change

Code:

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$edit = mysql_query("UPDATE trade SET habbo='$habbo', furni='$furni', amount='$amount', comment='$comment', password='$password' WHERE id = '$id'");

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too

Code:

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$edit = mysql_query("UPDATE trade SET habbo='$habbo', furni='$furni', amount='$amount', comment='$comment', password='$password' WHERE id = '$id'")or die("MySQL Error: <br>".mysql_error());

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and post the error message