The most common reason is that your WordPress is limiting the amount of Javascript loaded on your pages. Please Try to set:
define(‘CONCATENATE_SCRIPTS’, false );
in your wp-settings.php file.
The next possible reason for this is the amount of memory allowed for PHP on your server. Please check and make sure it’s not 32M or less. You need at least 64M, but if you have other plugins 128M or even 256M is recommended.
