Piwik couldn't write to some directories (running as user 'apache'). (no replies)

Hi,

I am just trying to get piwik to install on my system, but I just don't get through the first page:
[attachment 1931 piwik_error.png]
Stating that permissions haven't been properly set.
Nevertheless I made the required changes,
[attachment 1932 user_and_permission_settings.png]
but still it does not work!
Any suggestion would be welcome to get the settings right.
Many thanks in advance...