unable to set php to fastcgi and vps_optimized_mode_status missing in misc database

[longestdrive]

Hi
My set up is plesk 11.5 on centos 6.
I've been trying to install an additional php version - php 5.4 and the knowledge base step by step refers to ensuring fastcgi is set. http://kb.parallels.com/en/114753

I don't have this option in the host settings and found this knowledge base http://kb.parallels.com/en/114601

I've tried to turn off optimized mode but nothing changes. I've inspected the psa database - in particular the misc table but there is no entry for:

vps_optimized_mode_status

I've rebuilt the server twice to see if it changes anything but nothing happens.

So - how can I check if I have a corrupt install - can I do an update of plesk?

I'm very new to this so need all the help I can get

Main aim is to enable fastCGI

Thank you