A extensão Centos 6 PHP OCI8 não está funcionando (função indefinida oci_connect())

>     if (!$conn):
>                     /// INCLUDING ORACLE_HOME MANUALLY
>                             putenv("ORACLE_HOME=/u01/app/oracle/product/11.2.0/dbhome_1/");
>                            // INCLUDING LD_LIBRARY_PATH MANUALLY
>                             putenv("LD_LIBRARY_PATH=/u01/app/oracle/product/11.2.0/dbhome_1/lib:/lib:/usr/lib:/lib:/usr/lib:/usr/local/lib");
> 
>                             $conn = "(DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = xxx.xxx.xxx.xxx)(PORT = 1521))) 
> (CONNECT_DATA = (SERVICE_NAME = data)))";
>                             $conn = oci_pconnect("username", "password", $conn);
>                             endif;
>                             if($conn):
>                                 return $conn;
>                             endif;  
>                             if(!$conn):
>                                 redirect('login');
>                             endif;
>             }