autoload() problem

[eluser]Unknown[/eluser]
i want to up my database server always when i start the sight
so that i need to add

$autoload['core'] = array('database');

but i m using CodeIgniter V 1.7.2 (Current version) and i did not got that

$autoload['core'] = array('database');

in autoload.php file

so i cant use Scaffolding().

the page for that is comment but when i click that <Create New Record>
then i m geting


Not Found

The requested URL /index/blog/scaffolding/add was not found on this server.

but url is showing ,,,,,http://example.com/index/blog/scaffolding/add

plz help me . rally need help to solve this problem.