Hey my character cannot join zakum even when entered expedition. This happend to me yesterday too and i havent even done once today nor twice yesterday (only worked one) IGN: BrandDstrike
Any screenshot of the event would help to analyze the problem. Do you mean you managed to enter past the Zakum entrance, signed up to be part of the expedition but couldn't enter? What NPC message did you get when you couldn't enter?
It sounds like you had a click glitch. Were you even able to open the NPC dialog (that shows 3 options)?
Unfortunately, not one of our staff members has encountered any issues like this before, and we have had no player reports of any similar incidents. As such it may have been a problem of not signing up for the expedition before the run started, or possible connection issues. What I would recommend is next time you are signing up for a boss expedition like Zakum, Horntail, or Scarlion & Targa, to utilize a recording software. If the issue happens again this would allow us to look into the issue further.