[ASK]using sybase and got some message : could not find driver

[eluser]kun kun[/eluser]
hello everone, i'm using codeigniter 2.1.2 and using sybase for the database, i'm using PDO http://christopherickes.com/web-app-deve...deigniter/

and i all ready have php_pdo_mssql.dll in C:\xampp\php\ext, but i have message :'could not find driver' ; is there something wrong ?

[eluser]kun kun[/eluser]
is it impossible codeigniter connect to sybase ?