your web application must reside in public directory, like public_html, your domain must point to that location. Now, your yii framework location must not go here inside the public_html, it must go outside in order to protect your core files.
sample directory:
var/
yii/
1.1/
framework/
yii.php
public_html/
index.php —> include yii.php path, specifying the path outside yout public_html directory.
protected/
bla…
in this case yii.php is included using this settings in your index.php
<?php
error_reporting(E_ALL);
ini_set('display_errors','on');
$yii='/var/yii/1.1/framework/yii.php';
$config=dirname(__FILE__).'/protected/config/main.php';
defined('YII_DEBUG') or define('YII_DEBUG',true);
defined('YII_TRACE_LEVEL') or define('YII_TRACE_LEVEL',3);
require_once($yii);
Yii::createWebApplication($config)->run();
also, try using: “ini_set(‘display_errors’,‘on’);” (in index.php) to see what error occurs, and of course, provide logs.