A plugin which enables Magento's session to run within WordPress.
Check my blog for an example here
Check the Magento documentation
It means there's an error in your code. Set your PHP error_reporting to E_ALL and refresh the page so you can see what's causing the error.
Try placing the
error_reporting(E_ALL) without quotes at the top of the actual file you're working on then reload the page.
Try placing your
Mage::getSingleton(...) call at the top of your PHP file to prevent this error from taking place.
Check the screenshots area on how to setup the folder structure properly
Please post it to the WordPress support forum and tag your post with "mage-enabler".