There is a bug in Apple's disk image routines where it sometimes creates the disk image too small to hold the content. I know this is fixed in 2015 (we set the disk image size now instead of letting Apple's routines determine it).  I don't know if that fix has made it back to 2014 yet.  If it hasn't it will soon.  In the mean time you can make a backup just by copying or duplicating the company file