Auto Loader Problem

Hello
I have a Yii project , When I open my site in my local host it works good
but When I upload it to hosting it cannot auto load Classes

And I have error like
YiiBase::autoload(User.php): failed to open stream: No such file or directory (/home/myusername/public_html/protected/framework/YiiBase.php:421)

I run Yii Requirement Checker , and I see "Your server configuration satisfies the minimum requirements by Yii. Please pay attention to the warnings listed below if your application will use the corresponding features."

I use mysql so It also pass PDO extension and PDO MySQL extension
I dont use APC and Memcache and SOAP
why it cannot load some class and load some other class

it load $user = new User
but cannot load
User::model()
or
User::staticMethod()

just in webhosting , in local host all thing is ok