Expert mode, insert image and it puts an empty blank space in the music

I'm new, and vexed by crazy problem.  My objective is a simple picture slideshow of about 200 pictures, with about five different songs on the music line.  

I put the pictures in the desired order on the video timeline.

I put the songs on the music timeline.  

Sometimes the added songs cause the picture sequence to split open with a big gap.

If I add a new image somewhere along the timeline, it often causes a split in the music line.

I'm not understanding this software. There must be a way to stop this.

Photos: Sample1 shows photos lined up on timeline (about 3 seconds each)

              Sample2 shows adding the first song

               Sample 3: after adding a second song, the photo lineup splits.  Then any attempt

                                to move the photos back into place, results in the Music getting split.

Thanks,

Mark