$_SESSION is set to: FALSE - how can i change this with safety?

[prokopiss]

greetings

i am trying to install hesk help desk in a subdomain and i am getting error messages

in the hesk support forum i found this:
http://www.hesk.com/knowledgebase/?article=23

my problem is that the $_SESSION is set to: FALSE and that is wrong
so, can you please tell me how can i fix this problem to my installation? (i am on private server, with full access)

thank you for your time and for your support