Ubuntu bug about that: https://launchpad.net/products/evolution/+bug/39909

"calendar publishing refuses to allow anything other than "daily"

If i want to publish my calendar to my wifes a remote machine I might use the following procedure.

Open Evolution.
Choose Edit (menu) --> preferences
Choose calendar tasks (button on left panel)
Choose Calendar publishing (tab)
Click Add
Publish as: "iCal"
Publishing frequency "Manual (via Actions menu)" (I want to do this because I don't necessarily leave the machine on every day all day so would rather invoke the transfer when I want)
Sources "Personal"
Click Publishing location (tab)
Service type: SSH
Server: foo
File: /home/clare/alan.ical
Port: 22
Username: clare
Password: <her password>
Remember password: ticked

Click ok to save all of that. This returns you to the Evolution prefernences window. Now click the entry you just added and choose edit. You'll notice it reverts the publishing frequency to "Daily" rather than "Manual" as I chose."

Fixed most probably by commit [1], anyway, works as expected in 2.27.5.

[1] http://svn.gnome.org/viewvc/evolution/trunk/plugins/publish-calendar/url-editor-dialog.c?r1=34151&r2=34208