Which ICSdroid version are you using?
Can you provide the URL?
I have connected some Calendars on teamup.com. The Data were imported without a problem.
When the update (once every day) is triggered, it returns this message: “Unable to resolve host “ics.teamup.com”: No address associated with hostname”
Then I reset to only manual updates. After that I again set it to daily updates. ICSX5 then immediately fetches the calendars without returning any message. The updated calendar are available on the system.