Lahrs

In the Placid Waters facility, I'm unable to reach the fourth floor. I saw the elevator show Floor 4 once, but I went to the 1st floor, and never the option again. I have reloaded twice before entering the facility, no matter what I do, the 4th floor will not show up. I believe this is a bug and not something to do with quest options or order of completing objectives. Please help, I would love to get the information out of there before continuing my game.