Recently i noticed that when i burn movies the subtitles are left off of the copys. I'm not sure what's wrong?

Recently I noticed that when i burn movies the subtitles are left off of the copys. I'm not sure what i'm doing wrong. I use dvd fab to burn the movies to the computer and magic dvd copier to make the copys. it has really never gave me any problems. I'm not really good with technology.