I have created a set of LTI inks on one Moodle site, at a course level and used them to establish links on another Moodle site. After adding the URL and the secret I get a tick and a message saying Using tool cartridge. Then I save it and I get this error.
Interestingly I have already added this same link on the same course, on another external link and it works fine. If however when I make a duplicate of the external resource link the link fails to work. It links to the site but gives this error.
A required parameter (oauth_consumer_key) was missing.
In fact, I can not get any other link to work on this site. Why do I get this error?
Another interesting point is that on another Moodle test site I operate I have used the same URL to establish a number of different external links and they all work perfectly.
Has anyone got any ideas about this?