PHP4 and PHP5 together!

[rentasite]

Hi, this is not a 100% Elxis related question. But has to do with my Elxis environment.

I have set PHP4 as default on my server and PHP5 secondary. And now i want to use PHP5 on one of my accounts. I insert this peace of code in .htaccess

# Use PHP5 as default
AddHandler application/x-httpd-php5 .php

Is this correct? And if yes, why doesn't it let me get in the Elxis Admin area? I login and the browser just refreshes and bring me back to the admin login page. 

I also get these errors on top of my homepage:

Warning: session_start() [function.session-start]: open(/tmp/sess_06625f5d737db0fb67694e0cbcbb9a04, O_RDWR) failed: Permission denied (13) in /home/blabla/public_html/index.php on line 17

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/blabla/public_html/index.php:17) in /home/blabla/public_html/index.php on line 17

[rentasite]

Update

SOLVED

It didn't let me in the admin area, cause of a cache issue. Everything ok now.