Another upgrade error

when i upgrade ojs from 3.0.1 to 3.1.1 everything goes ok, but site don’t display css, or images…
here are some errors from log…
mkdir(): Permission denied in /var/www/html/ojs/lib/pkp/classes/file/ on line 289
PHP Warning: assert(): Assertion failed in /var/www/html/ojs/lib/pkp/classes/scheduledTask/ on line 57
PHP Warning: fopen(): Filename cannot be empty in /var/www/html/ojs/lib/pkp/classes/scheduledTask/ on line 111
PHP Warning: flock() expects parameter 1 to be resource, boolean given in /var/www/html/ojs/lib/pkp/classes/scheduledTask/ on line 112

permision are all ok, 777 on file system. Help?