get_instance() undefined in custom librairies ? :(

[eluser]doMynation[/eluser]
Good day,

Although I've seen many people pretending to do it without any error, I just can't access the CI core base using:

Code:

$CI =& get_instance();

It says the function is undefined.

I need to load some CI ressources (helpers for example) within my library. Am I doing something wrong ?

Even the user guide says it's the way to do it: http://ellislab.com/codeigniter/user-gui...aries.html

Thank you !