error activating plugin, no admin window

I tried to activate a plugin but it don't work, for some plugins that have admin window, it don't show.

I get this error in apache error log:

PHP WARNING: "unlink(/var/www/elgg/view_types): Permission denied" in file /var/www/elgg/engine/classes/ElggFileCache.php (line 158), referer: http://localhost/elgg/admin/plugins

I tried changing the permissions of data and elgg directory but still in the error