I can't see the content of my backups

Hello everyone! I uses in MacBook , 11 inch, operating system MacOS10.12.6.
Wen i in to to my backup drive i can be able to see the backups, i can see the date and the syes of the backup, but wen i entering to my backup that i was choosed i can't be able to see the content. however folders is empty. it does need to be like this? I remember that in the past i could be able to see the content and now not. Thanks