I'm developing a tool provider for a Moodle instance and having trouble submitting grades back to Moodle. Attempting to POST to mod/lti/service.php throws a 404 error & the message 'Consumer key is missing.' (after turning on debugging).
I've verified that my tool is producing valid OAuth headers and have even tried POSTing manually generated OAuth headers (both via the 'postman' chrome extension). As far as I can tell, the submitted XML is valid, though I don't think that's ever evaluated.
I'm kind of at a loss, here. Anyone have suggestions for further inquiry?