Bioshock Burial At Sea glitch #2

So I am at the appliance section of the DLC where you have to get to the central exhaust to find Sally but I am at the door where it is SUPPOSED to trigger Elizabeth trying to get into the small opening next to the door but when I try to open the door it doesn't trigger like it is supposed to. Elizabeth is supposed to offer to go through a small opening after trying to open a locked door in appliances but instead she just stands there and follows you like normal. Am I doing something wrong? I close all the vents like I was supposed to.