with my machine it worked with
user: hte-user-i-am-logged-in
group: www (the apache group)

the rights (chmod) should be 750 or rwxr-x---

if you donīt know what this means, open the terminal and type:
man chown (owner and group)
man chmod (the access rights)

both commands chown and chmod have to be run as sudo.

hope this will help you