Could not find My_Controller

[eluser]ENG.Helewa[/eluser]
Hello,,

I have some problem. Recently i have moved to linux and i faced this problem:

Code:

Fatal error: Class 'My_Controller' not found in /var/www/html/test/application/controllers/welcome.php on line 3

i tried many solutions including putting My_Controller in application/core but nothing changed.

help please.
thanks in advance.