The loader expect all "Crt_" objects to have their pivot point at (0, 0, 0).
If the pivot is centered on the object, then its bounding box is wrongly calculated, and then when you add seats, they are seen out of all bounding boxes, which leads to the crash...

BTW, right now, you put 2 seats together, so u'll get 2 people on the same place...
Also, I did a mistake in the explanations at 1st ; board name should be "BB_ServSpd" , not "BB_ServeSpd" ;