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so, is there a secret level where you can save your brother? or is that going to be in the sequal, if they make one?

I am having trouble entering the door to the kitchen on the Singapor Sling level. I have killed all of the japs, have tried restarting the level, have looked up several walk throughs and have even followed my buddy to the hallway where he disappears, then down the stairs killing the guys in the back room but still this door is not or will not open for me....am I going to the wrong door? where do I go from here?