Hi, i've tried to install zenphoto on my mac with a XAMPP (Apace Server, MySQL, PHP etc.. )
and riecieved a message that the album and the cache dir is not writeable.

i've changed both via chmod to 777 and in the finder it is shown a write/readable too..

the php safe mode option in the php.ini is "off"

what could be the reason and how to solve it?

Generally that should work fine (I use MAMP), try setting the rights in the finder, too.