php - blank page opening after uploading codeigniter code to server -

i have uploaded codeigniter code server blank page displayed when opening url

i using codeingniter 2.1.3.

i used my_controller.php on application/core/ folder per specification

i got error in error_log file of codeigniter

"php fatal error: class 'my_controller' not found in /home/nesterin/public_html/realstate/application/controllers/administrator/login.php on line 3"

can tell doing wrong ?

i'm not familiar codeignighter. think if class name my_controller , it's filename my_controller.php autoloader won't find file on case sensitive file system.