Video not playing during timeline preview?

I am having a similar issue.  I have created a training video and needed to cut dead time from the videos so I did this by cutting the videos into smaller segments and aligning them back to back.  When I first did this, it worked fine, now it is only playing the first video in the sequence.  Is there something that I need to adjust to get it to play all the videos back to back as designated in the timeline?