DFSR shared folder access denied

I support an environment using DFSR as a backup, 1 target folder accessible to everyone and the other only accessible to domain admin/local admins. I know it is not a regular configuration but it works fine, everyone can access to the shared folders except 2 users. they get the message "Access is denied". when I delete the only-admin-accessible-folder from DFSR configuration, they can access to the folder, but after checking the access and rebuild the only-admin-accessible-folder, i get "Access is denied" again.

Those two are using client machine OS Win7, but there are other users with Win7... so I stuck here. Since the configuration is not normal, I cannot find the answer elsewhere.

Any tips can be very helpful.

Thank you in advance.

ssmh