Thanks for the speedy reply.
The directory for the albums and subalbums is as follows:
/public_html/development/zenphoto/albums/top-level/album1
/public_html/development/zenphoto/albums/rop-level/album2
/public_html/development/zenphoto/albums/top-level/album3
etc.
The sub-albums display under the top-level album as, e.g.:
album1
album2
album3
I am trying to list the sub-albums so that they display in a particular order, as advised on the "Edit album" page where it says: "Drag the albums into the order you wish them displayed."
So I want them to display under the top-level album as, e.g.:
album1
album3
album2
The albums can be moved with my mouse to the correct positions, but when I press "Apply" I get the error shown and the albums are still in their original order
I'm sure I was able to do this before but now it seems to fail as indicated in my original post.