Problem With Showing Images

in my app when a user adds a post he also upload an image to this directory:
/uploads/images/ads
in time of showing these images i write this code:

<img class="adpic" src="<?php echo CHtml::encode(Yii::app()->baseUrl.'/'.$data->pic); ?>" />

that $data->pic is uploads/images/ads/somepic.jpg

on localhost its working but not in my online site.
even in online site's source code url of image is correct and by clicking it shows
the image but not in web page itself.

can anyone help me?
thanks