Session ID invalid?

[Sweve14]

I have a good session ID logger and am using the .jar to try to log in, we are using my friends acc to test. Anyway, they log on and join a server. I then take their ID name and UUID into your script. I can confirm it correctly changes the optifine code. I then log on using a different account from the one i am logging and join using optifine 1.2.2 client. From this point i am in the multiplayer menu but whatever server i log into says invalid session, even the server my friend is currently on. Trying to use this for skybock if u know what i mean but i can not figure out how to correctly use the script that opens the session id. Thanks for the help im sure im doing smthing wrong but im pretty lost rn