[pmwiki-users] Install, blank page, session_name() error

[info at hassanein.ch]

Hi all

I installed pmWiki several times successful but now I face a problem.  
Please find following the set-up:
Linux/Suse(SLES9)
Apache 2
php V4.3.4
pmWiki 2.2.0-beta29 and latest stable

After the installation I get a blank page. I traced it down to the  
following line in pmwiki.php in function SessionAuth (The code after  
this line will not be executed):
"if (!auht && ($called>1 || !@$_REQUEST[session_name()])) return;"


When I put an additional session_name() call before this line, I get  
the following error:
"Fatal error: Call to undefined function: session_name()"

Can anybody explain this behaviour?
--
Any help is very much appreciated.
Regards,
Mike