Magento-How can i override admin module correctly

Hi friends:

I have overrided some modules : "Enterprise/Pci/Model/Observer.php","Mage/Admin/Model/User.php","Mage/Admin/Model/Session.php","Mage/Admin/Model/Observer.php".

And configuration as follows(config.xml):

`<global>
    <models>
         <Pci>
             <rewrite>
                   <observer>App_Pci_Model_Observer</observer>
             </rewrite>
         </Pci>
    </models>
</global>`
....

`<global>
    <models>
         <Admin>
             <rewrite>
                   <observer>App_Admin_Model_Observer</observer>
                   <session>App_Admin_Model_Session</session>
                   <user>App_Admin_Model_User</user>
             </rewrite>
         <开发者_运维百科/Admin>
    </models>
</global>`

but it doesn't work, my code is not run.

Any help is greatly appreciated.

The module names are case-sensitive. Instead of <Admin> use <admin>. Instead of <Pci> use <enterprise_pci>.