This is really perplexing me. Because it worked fine on the staging site, that would seem to suggest that the code I wrote is OK, and because the previous version works fine on the live site, that would suggest that the server is OK. Does anyone have any experience with this problem?
I've attached what I got from the Firebug console- some sort of 500 error involving Ajax, I think.
I'm using Silverstripe 2.3.3.