Don't get discouraged, at all!
If it doesn't work then keep trying. As long as you're not blacklisted by PMI (and you will never be if you don't cheat) then you can still take the exam, and you will eventually pass. Trust me.
The important thing is to think the same way that the PMBOK (or PMI, if you want) tells you to think when you answer questions on your PMP exam (and not to think the way you manage your projects). Even if it doesn't make sense or even if you know it's wrong, you have to think THEIR way to pass THEIR test.
Good luck and hopefully you'll pass the PMP on your fifth try!