Migration from 1.7.2 to 2.0 and respectively to 3.0

Hello guys. 
I have the task to migrate a codeigniter webpage from 1.7.2 to 2.0 ( 2.2 ) and then I need to migrate it to 3.0. 
I followed this particular guide: http://www.codeigniter.com/user_guide/in...e_200.html
And after I did everything I uploaded it to the ftp and now I am getting a blank page. 
I think I've got all things done as by the tutorial but even if I have missed something I at least need an indication for that. But I am getting nothing - blank page. 
I enablet error_reporting - nothing 

Configed the log_treshhold to 1, and again - nothing 

It's very important so pls, help me. 

Best regards, 
g3n1u5

[Image: http://g9m29.com/random_images/signature.gif]

most likely missing some required php extension

Can u plase, tell me a bit more. Where can I find those extensions, and how to activate them?

[Image: http://g9m29.com/random_images/signature.gif]

if you use webhosting, in their web admin panel

It was very interesting very very intresting case. A file I have added was listed as missing I mean the file was there but the code somehow could not read it. I just uploaded it again but now I have a new problem.

I updated all files and when Controller or Model is called, I should extend CI_Controller or CI_Model, but it gives me error, and when I changed it ot Controller or Model only it worked. But now I get this error ->

Call to undefined method CI_DB_mysql_driver::order_by()

And I think it's because I've missed something. I've written

$active_group = "default";
$active_record = TRUE;

But it's not working.
I don't have datamapper so I cannot ad it in the index.

What should I do to get rid of this problem?

[Image: http://g9m29.com/random_images/signature.gif]