well, i think you gonna be disconnected 'cause you edited the .swf
maybe the server validates the hash of the client and if you edit it the hash changes, too.
I successfully hacked a flash game called "icy tower", it's a "app", it is embedded in a sozial network, similar to facebook...
The server validates the client (however, but i guess its hash)
in my case the swf called the site .../verify.php and i found a list of return values: "VERIFY_FAIL" and so on...
I would change the url to your own verify.php which returns "VERIFY_SUCCESS" (for example)
Or if you find the verify function you can just delete its call or content...
I don't know the game, but do you have to logg in the website?
If this is the case, its just because you don't send the session cookie...
Then you have to send a loggin package, which posts your acc datas, then you resieve a http header with a cookie identificates the session...
Then you send your request of the .swf and append the cookie...
I hope i could help you, of course you can ask again

Sorry that i ended pretty many phrasres with "..." and for my english...