File upload(mp3 and pdf files)

[eluser]Unknown[/eluser]
how to upload mp3 and pdf files in databases using codeigniter.
when i try it says

The uploaded file exceeds the maximum allowed size in your PHP configuration file.

pdf files which have to be downloaded is more than 2MB so please wht to do plz any1 help.
the code i gave is

$config['allowed_types']= 'pdf';
$config['max_size'] = 1024*1024*2;

but it is not working!!!!Plz Help