This user has the following games installed:
Sims 2, University, Nightlife, Open for Business, Pets, Seasons, Bon Voyage, Free Time, Apartment Life
Shuttle won't come, game refunds vacation
So one of my families booked a vacation ages ago and now the vacation is supposed to begin the game just shows the message: "It appears that no one in the family can lead the vacation. A refund will be issued right away." I have three elders and one teen from the family that have to come with and 4 sims from outside the household (3 children that have gone to university with one of the lovers).
The only thing I can think about is that some of the sims that are supposed to come with have since then graduated and the game is now confused somehow.