Sending score works inside Flash, but not elsewhere

Hi,
I’m creating my own highscores table for a flash game.

When I send a score from inside Flash, it works. The score is sent to my php file located on my website and to my sql table with no problem.
But, if I try the .swf in my desktop for example, it fails to send the scores. And if I upload the file on my website too.

So I guess this must be some kind of security issue?

Before you ask, in publish settings the local playback security is set to “access network only”.

Is anyone familiar with this problem?