Captivate 7 elements of project go missing when publish to mp4

hi,

i have created a short captivate software simulation project containing slides and audio.  It all looks fine in Captivate - whilst on the screen display or when I run it as a project from beginning to end.  However when I publish it to MP4, it loses some of the visual images on the screen.  Either they disappear altogether or they become distorted.  I have recreated the mp4 again, but the exact same thing happens.  Any ideas why this would happen? and what I can do to stop it happening?

Thank you,

Lisa