strange, worked perfectly for me. any idea what the problem is? just a thought, but maybe you need to set mydrive.ch to use https rather than http. i think there's
the server url to use is https://webdav.mydrive.ch .
mydisk.ch is a free service that works with zotero. there's a 2 Gig limit for the free service and individual files can't be bigger than 2 Gigs. Accounts are easy to set up to work with zotero. Highly recommended.