Do I need to change a setting somewhere?
<?php Loader::element('footer_required'); ?>
I'm thinking the simplest way round this may be just to rebuild my catalogue page.
The piece of code above must be in your source files (on the server).
I answered some theme related questions and also suggested some links for a deeper understanding in this post:
I suggest you head over to that post and also read the first link in the same post.
Thanks for the hints. Just in case anybody has the same problem and comes across this thread in their search for an answer, I thought I'd better post a note about what turned out to be going on in the end. I noticed when I tried to rebuild the Catalogue page from scratch that it seemed editable up to a certain point, and then all of a sudden the editing panel at the top of the page would turn into a blank grey bar. Eventually I went back and tried it again, adding elements to the page one at a time, and it became apparent that it was becoming non-editable as soon as anything to do with the e-commerce add-on was used - either an item for sale or a link to the shopping cart. So then I downloaded and installed the most up-to-date version of the e-commerce add-on, and immediately everything started to work properly.
What's going on?