PHP and MYSQL Update problem

Hello,
I have a little problem with a sql command string

$q = "UPDATE episodes SET episode_title = '$_POST[episode_title]' ,
episode_scheduleddate = ".strtotime($_POST['episode_scheduleddate'])."
, episode_description = '$_POST[episode_description]' WHERE episode_id
= $_POST[episode_id]";

I keep getting this error

You have an error in your SQL syntax; check the manual that
corresponds to your MySQL server version for the right syntax to use
near ''

which doesn't help a lot. I've already tried to print the result

UPDATE episodes SET episode_title = 'Title test 1 edited 2' ,
episode_scheduleddate = 1232427600 , episode_description =
'Description test edited' WHERE episode_id = 1

I really can't find the problem. I tried almost every combination with
' and " without any result.

Thank you.
Simon.