OpenX 2.8.1 Login Page Warnings: directory plugins is not writeable

OpenX 2.8.1 Login Page Warnings: directory plugins is not writeable

Stupid Problem: Stupid warnings when login to OpenX 2.8.1
Stupid Solution:
1. delete files in /var/cache folder
2. download all files in /plugins
and upload again
and set all files with "777" as forum said
but this time files are owned by you, but not owned by apache

Hope this help