php_value extension is ignored

I have a server that runs the bellow perfectly (Apache v2.2.14 & PHP v5.2)

Testing on new one the zend_extension is completely ignored but post_max_size is updated as should (Apache v2.2.22 PHP v5.4)

<VirtualHost *:81>
    php_value post_max_size 50M
    php_value zend_extension /<path>/ioncube_loader_lin_<php-version>.so
</VirtualHost>

If, however, I add IonCube to php.ini as

zend_extension = /path/ioncube_loader_lin_<php-version>.so

it works perfectly. I would like, however, to keep it on a per VirtualHost-basis. Does anyone have any ideia what could be causing this?

Solution

As per the documentation, zend_extension is one of those directives that can't be set this way. It must be set in php.ini.