Where are you getting the disk image from? It is possible that the disk image is damaged, or badly made etc. Disk images can store items in the trash too, so check that there is nothing added to your trash when the image is mounted.
It is also possible that the disk image contains hidden folders in which case it could be normal to look empty in Finder. Make sure you are changing the view type (view as a list or in icon view in Finder) incase the file(s) are simply out of view.
Disk images can also have a fixed size, so again it could be normal to be a 71MB container even if no data was added to the 'virtual volume'. You may want to confirm where you see the size, for the disk usage of the volume or for the space that the .dmg file consumes?
I'd suggest you look at where you are sourcing the disk image form, they may have other versions for download or have support that can help. Also avoid getting software from anywhere but the original developer. Some 'software download aggregators' are bundling malware or adware with some apps. Reputable developers don't normally do that.