The newer versions of facebook work on the newer versions of BlackBerry OS. We're currently at OS 7.1 but I suspect your phone is still running OS 4 or OS 5. You'll have to revert to the previous version or upgrade your phone.
I hope that helps you. 
- If my response has helped you, please click "Options" beside my post and mark it as solved. Clicking the "thumbs up" icon near the bottom of my response would also be appreciated.
My Z10 was furnished by BlackBerry but all opinions are my own.
