Fatal error: Class 'PDO' not found

[WffUser001]

When I submit form, I see

Fatal error: Class 'PDO' not found in /home/sirsoftc/public_html/
_mpiasta/form/objects/class.database.php on line 21

And right before that, it said:

Could not find wff_misc.php. For some reason, the form file looked
like :

include_once("../configuration.php");
include_once("../objects/class.database.php");
include_once("wff_misc.php");
include_once("../objects/class.mytestwff.php");

I had to manually point wff_misc.php to the objects folder...

include_once("../objects/wff_misc.php");


And before that, I had POG error. So I had to change PHP 4 to PHP 5.

This is a lot of B.S. lol. Does this script even work?