Laser designator not working

[Strother 0]

Hey, I'm having troubles with my Laser Designator. I'm making a MP coop mission where you need to laze a building, well it was all working fine and I was getting the lockon box to show and the bombs to hit, then randomly tonight, the lockon box stopped showing up. . The only thing I can think of, is that I alt tabbed while in the mission editor and I went to watch the Ball Drop, I came back and no more box....