doctrine load error

[eluser]Unknown[/eluser]
I installed doctrine and I ran the hello.php file as mentioned in this tutorial : http://www.phpandstuff.com/articles/code...ment-18493
and i got this fatal error...please help

Fatal error: Class 'User' not found in /home1/rahulurs/public_html/code/system/application/controllers/hello.php on line 12