Cannot edit or create new orgunits

Whenever I try to save an orgunit in the online demo at the link below, I get this error, which I think is only supposed to have to do with six-monthly periods (and thus seems like a strange error to get when I am working with orgunit startdates):
Month not valid [1,7]


Knut Staring

Dept. of Informatics, University of Oslo

Norway: +4791880522

Skype: knutstar