Symfony error: couldn ' t locate driver named MySQL, how to handle

Symfony error: couldn ' t locate driver named MySQL
Title, using symfony1.4, data model and so on command line connection database are automatically generated, during, no error. At run time (Connect database query data), Error: 500 | Internal Server Error | Doctrine_connection_exception

Couldn ' t locate driver named MySQL.
Well, the configuration of php.ini using MySQL database is all open. Why is it wrong? Why is it???
Configuration database files, using the DATABASES.YML,

PHP code

  
  All:  doctrine:    class:sfdoctrinedatabase    param:      DSN:      mysql:host=127.0.0.1;dbname=hr_ Administration      Username:root      

------Solution--------------------
With the answer to another similar question, you may not have the path to the PHP extension configured.
PHP.ini's Extension_dir
The most effective solution is to check the Apache or PHP error log

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