[PHP/MySQL] Having trouble with an UPDATE query

Hey, boys and girls, I need your help, please (before I lose all my hair).

I’m doing a cms type effort for uni and I’ve hit a big hurdle at the ‘edit news’ page.

Basically, when I click ‘edit’ it tells me everything has been edited successfully, but when I check the db nothing has changed.

The only thing I’ve learnt so far is that it’s having issues with the variable being used in the WHERE syntax

$edit= "UPDATE headline SET headline ='$postheadline', about ='$postabout', story ='$poststory' WHERE ID='$id'";

                       mysql_query($edit) or die(mysql_error());

I’ve tried removing the quotes around it, only to get a syntax error telling me to look at the text near " on line one.

I also echoed the $id variable outside of the form and it echoes the said post ID without trouble.
As well, I changed the variable in the update syntax to an actual post id (like 11 or 3) and it changes the information there.

I’m an immagrant who’s arrived in PHP town recently, only knowing a little bit of the towns language!

If you have any lights spare to shed on this situation, please lend me them.

Tom