PDO_OCI: could not find driver

Today my problem is connected with PDO, OCI8 and PDO_OCI. But from the beginning.

I'm using Ubuntu 11.10 and PHP version: 5.3.8-1ubuntu3. I have installed Oracle 10g Express, configured it and it works fine. The next step I had to do was integration between Oracle and PDO. So I found this link: http://lacot.org/blog/2009/11/03/ubuntu-php5-oci8-and-pdo_oci-the-perfect-install.html and do it step by step (without instaling PDO, which was installed previously with pdo_mysql). When I tried to do it on Ubuntu 10.10 - it was working. Now, on 11.10 I get an error: 'Could not find driver' when I try to open my website application.

I checked phpinfo() and in the row PDO there are: PDO support - enabled, PDO drivers - mysql. There is nothing about oci in this section, although few lines under it I have PDO Driver for OCI 8 and later - enabled.

Hope somebody can help with this. Best regards, Mateo.