Problem/Bug CraftBukkit Tab-Completion not working

In my server that I play with some friends, tab completion is not working for them. I am oped, and it works for me, but after I de-oped myself, left the game and came back, I could no longer do tab completion. The commands would also have red text like I did not have permissions for them, but would still work. Is there a permission I need to give to allow tab completion? If so, what is the permission?