The only thing I can guess at is that you haven't waited long enough for Zeltan to come back and tell you the party has been set up.
Update 1.7
In the link about update 1.7 it says you need to wait for 5 days.
Any time I needed to wait for something to happen, I would go sleep in the Medbay and then mess around on the ship for a little bit, then go sleep in the Medbay again and keep repeating that cycle of just idling around the ship and sleeping.
If you are positive that you have waited 5 days, by sleeping in the Medbay, and nothing has happened, I don't know what to tell you about it.
I remember it taking forever for the event to trigger, but that is about it. Just make sure you sleep in the Medbay and not in the lab in the Vents.