Can't Open Folder on Backup Mounted volume

I cant’access to bakup folder User on my backup, only folder User other folder i can read!
I try to modify security setting, but always i got an error, it’s impossible to modify a security setting!
I got Administrator privileges but i’s the same

I read this topic

and this;msg503440#msg503440

But the solution doesn’t work!

The backup must be mounted in read/write mode to change security settings.
Please post a screenshot of the error you get.