[Installation Error Message "session save path ..."]

i have installed the latest version 4.0.1

after i tryed with 4.0.0

the error with both versions is exactly the same

[Installation Error Message "session save path ..."]

Hi,

i want to install the adserver. when i try to do i get the following error message appears in the browser window:

The session save path '2;/var/tmp' is not writable.

in the url line there is written:

http://domain.com/adserver/www/admin/install.php

can somebody help me and give some tipps for solving the problem?

 

thanks