Yea I seem to have the same problem, the other two campaigns unlock easily but that middle one refuses to unlock. At first I thought it was because of the glitch on the Mad Hatter fight that while going from the second door to the connecting door upstairs the character would get stuck and in doing so would make it impossible to complete the level.
Ah well I'll start again, it might be more fun unlocking the characters myself, and I got all the extras using codes (well actually i edited the exe so they were AAAAAA AAAAAB etc )
I think using the character unlock inadvertently blocks the lvl2 games for villans, I found the batboat was unavailable also when in free play on world2-2. I ended up replaying world2 through to completion to access all missions. I have'nt used the unlock characters as yet within this new game but can vouch that the health & money trainer options do not cause any issues.
with the codes, the trainer isn't really necessary I find; just unlock all extras and suit upgrades and it's cool. I just wish there was a studs cheat in the million stud missions
i find the lego games easy as they are- i have never found it necessary to cheat or use a trainer.
I think the best way to do it is normally- at least until you've unlocked all the missions
--------------------------------------------------------------------------- as you stand, gun in hand, ready for the attack. The calm before the storm is broken...BANG...headshot from a sniper. I wait in darkness until the opertunity arrives- picking my timing and position, seeing the whites in your eyes before the trigger is pulled and life fades from my opponents.