STALKER lost alpha... help?

i downloaded and played my way through to the end or so i thought.
i ended up with the monolith ending for immortality but as any 1 who has played stalker before knows thats the bad ending, you guessed it i missed something.
i went to rooom 26 and met ghost but didnt pick up the code so when i relised this i went back to find an emty room... is this what i missed?
the real ending seems much harder to get so im wondering what i missed to get it.

any ideas. suggestions, tips welcome...
 
i got it soreted about 3 weeks back... the captain i was supposed to get the number off got killed in my first attempt.
anyways i finished it and while its not exactly a AAA title its decent enough to warrant you all downloading it and giving it a go... its free so why not...