WebDAV Guest Access?

I have the Public folder on my Lion Server set to allow Guest Access. WebDAV is also enabled. "Others" have read-only access.

When I "Connect To Server" "https://server.domain.com/webdav", the "Guest" button is enabled. When I try to log in as Guest, I receive the error message: "There was a problem connecting to the server..."

The log on the server shows:

[23/Jul/2012:10:52:08 -0700] "OPTIONS /webdav/ HTTP/1.1" 401 538 "-" "WebDAVFS/1.9.0 (01908000) Darwin/11.4.0 (x86_64)"

"401" = Unauthorized

The log on the client machine shows:

7/23/12 10:46:55.869 AM webdavfs_agent: network_mount: network_getDAVLevel returned error 1

Log-in to the same address as an authorized user works as expected.

How do I connect to a WebDAV Lion Server file share as a Guest?