Webdav repository not functioning

Unable to get a file listing from a webdav repository. Used a public test server - same results. Able to view files in public webdav from moodle server (to rule out firewall) from internet explorer and mapped drive.

Public server: http://code.google.com/p/sabredav/

Moodle configuration as per screen attachments.

Tried personal webdav server (used by staff for a number of years) garners "Invalid JSON string". Personal webdav uses HTTPS with 'basic only' auth (no HTTP fallback or redirect) and a nonstandard port 8440 - both inputted into the correct boxes in moodle.