Game Glitch?

[toxicpinball8]

I'm on the mission where you have to rescue Karen, but in block B-2 every time I pick up the red key, the door still won't open! I've even ran through it couple times just to be sure. I've explored EVERY inch of the map, and the only explanation is that the key you get right in front of the door, is the key to the door, but it still won't open!

[InajaD]

Sometimes you need more than one red key to open a certain door. Just check your map for areas you haven't been yet, but most importantly, check the msg you get while attempting to open the door. The same happened to me earlier in the game, and i just wasnt reading the msg, something so simple....
good luck