Scientist career problem

Lately I have had trouble with my scientist, if I want him to stay and work late. Then when he should go home, he stays at the science station. No matter what I do, he is still at work, even if I let other sims invite him back home and will not start a new day. At last I had to let him quit his job and start all over. I have done this several times now, and it is annoying me. Does anyone else have the same problem, and will it be solved?