Sims won't go to work. [ Edited ]

[juliabam123]

I paid some closer attention to their behaviour when going to school. Sometimes they go to school fine. But sometimes they dissapear at the elevator of the appartment, start waving their arms (the way sims do when they can't reach a certain object). The routing error message appears above their head, and they walk back inside. When I press 'Go to school' after they reappeared, they always go to school fine.