Sessions Errors when using regular PHP sessions

Hello:
Im trying to implement a simple captcha on Nette version 9. where i using plain php sessions but i keep getting this error:

Warning: session_start() [function.session-start]: Cannot send session cookie – headers already sent by (output started at /temp/cache-Nette.Template%00b67c8f908d71b685776237e9d7436ebe.%40layout.phtml.php:15)

here is a link to the simple php capcha:
http://www.abeautifulsite.net/…tcha-script/

The problem is i looked at the documentation and tried to use the as sessions as noted but it completely broke the view. not sure where to take it from there.

greatly appreciated.