Are you talking about Ioncube's PHP Accelerator and Zend's Optimizer working together? I've never had any luck getting that to play nice together. I always end up losing the Accelerator no matter which script I loaded first.
they can work together fine....the lastest version of zend optimizer is 2.5.1
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That image you posted is using IonCube loaders along with Zend Optimizer and that can be done with no problems. The compatibility issue is with using Zend Optimizer and Ioncube's PHP Accelerator. Zend certainly does not want you to be able to use a free PHP Accelerator along with their Optimizer when they get $295.00 minimum for their Accelerator license.
I would love to see someone who has IonCube's PHP Accelerator and Zend Optimizer running together on a shared environment. It may be possible somehow but I haven't seen anyone do it yet...