SOLVED - don't know how, don't know why.

Hi, I'm using Thunderbird 31.3.0 on win8, set my archiving options to "yearly folders" & maintain subfolders. Clicking the archiving button does create the respective subfolders in the 2014-folder of the archive, but it doesn not move the message. However, for messages from 2013 it works. So archiving in general and the IMAP connection to my mailprovider seem to work. Thunderbird just doesn't move the 2014 mails over. And I even cannot drag&drop them manually to the folder. My account is almost full, please help