Quote Originally Posted by maria82g View Post
main_page=checkout_payment&error_message=MODULE_PAYMENT_2CHECKOUT_TEXT_ERROR_HAS H_MESSAGE
The text IN_ALL_UPPER_CASE is indicative that the module hasn't been fully/correctly installed.

Common causes are the files have been uploaded to the admin folder rather than the main folder (or vice verci), or the files have been placed in a folder literally called "CUSTOM" rather than the foldername of the template being used.

There are other possible causes too, but those are the most common.

Cheers
RodG