Try adding it as a networked calendar, with the file:/// prefix to its pathname in the "location" box. .

Thanks for your reply, Zenos. I tried it, but it doesn't pick up the old calendar -- it just creates a new empty one. The dialogue doesn't indicate that it couldn't find the file that you were trying to attach. For the time being, I 'imported' the calendar.

I see that the ftp protocol is supported, so I'll try installing that and search for the file that way (i.e. ftp://.......)

I installed ftp (actually vsftpd) on my server and could connect to my calendar using ftp://...etc....