Permission deny after copy file

[jiandingzhe]

After I copied some files from one computer (linux system) to another (linux also), the files are not able to be accessed by normal account.
As it can be accessed by root, I chown those files to my username, but still cannot be accessed. While I try to ls -l those files, the accession limit, user and group are all displayed in "?", but can be seen normally when accessed as root. I guess it is something about security, but ls -Z provides same context as other normal files. What's the hell over there?
Thanks!!

[falko]

Can you post the output of

ls -la

(run by root)?

[jiandingzhe]

I found if the whole dir is not set to 755, the problem occurs. The dir is previously set to 644, and there are files inside the dir set to 755. But why?

[falko]

Directories must always be executable.