Piwik session error

Hi,

i installed piwik and everything is working grate, but when i try to use the API in the PHP to call some action i get an error that the session has already started (and it’s true because i have session_start() that i need before calling the API) and when i tried to define PIWIK_ENABLE_SESSION_START to false it gives me this error “Unable to start session. Check that session.save_path or tmp/sessions is writeable.” and the folders are fine…

how can i solve this problem?

Can you please put up some code so we can replicate the issue?