Thank you for your response.
My tablet has been having this problem for about one month. It might could started after I had updated my Samsung Cloud App..I would like to tell you that sometimes my Gallery pictures sync automatically with Samsung Cloud, but that happens very seldom.
Approximately since then auto backup has not been working also.
I tried to delete and reinstall my Samsung account. That did not help. Several times I cleared data on my Gallery App.. Several times I cleared data on my Samsung Cloud App., and after that auto syncing worked perfectly, but for a short time.
Thank you.
Sincerelly.
Alexander Reznik.