Demo content

Hello
I’m trying to install the demo content, but it redirect me to:
“wp-admin/admin.php?import=wordpress&step=2″

and I get an error it says.
404 – PAGE NOT FOUND
The page you are trying to access does not exist!

By the way, I’ve added the below lines to the wp-config file.
define(‘WP_MEMORY_LIMIT’, ’512M’);
ini_set(‘max_execution_time’, ’180′);

Thanks