The cacti user admin under lnmp cannot log on

Source Code Compiled lnmp, download the cacti-0.8.7h, found in the home page after login, the page will stay in install. PHP, the page is blank, until now do not know why, my PHP is 5.4.26, do not know whether it is caused by the difference with the PHP version used by cacti, or what is going on, so far not tomorrow, since there is a problem with the cacti-0.8.7h, new version of The cacti-0.8.8b, the home page opened, but with admin and Admin is always unable to, login database, after changing the admin password, it still does not work (use cacti; update user_auth SET Password = MD5 ('000000') Where id = 1;). The problem should not be in the database and be checked online, I learned about the permission issue of/var/lib/PHP/session. I can give it a 777 permission.