Problem to move from ical1 to ical2 - horde, kolab 2.2.4

[Michael Riehemann]

Hi List,
i have two calenders, lets say ical1 and ical2.
Both are new, local kalenders created by myself.
If i try to move an event from ical1 to ical2 i get the 
error: "Beim Verschieben des Termins ist ein Fehler aufgetreten: IMAP-Fehler. Ordner: . Fehler: Mailbox does not exist."

maybe in english: "while moving the event an error, Mailbox does not exist. 

If i make a new event in ical2 or ical1 there is no Problem.

Can anybody point me to the right place??

King regards 

Michael