I guess it is another newbie question, but I can not save data to the DB: I open the DB like this: self.st = FileStorage.FileStorage(self.mountedDB) self.db = DB(self.st) self.connection = self.db.open() self.dbroot = self.connection.root() self.dbroot = OOBTree() return (True,'db mounted:'+ self.mountedDB) Next I make a number of changes to self.dbroot: self.dbroot[CstNo] [FY] ['1'] ['E'] = {} self.dbroot[CstNo] [FY] ['1'] ['S'] = {} self.dbroot[CstNo] [FY] ['1'] ['accno'] = {} self.dbroot[CstNo] [FY] ['1'] ['acba' ] = {} self._p_changed = 1 get_transaction().commit() And then I close: get_transaction().commit() # commit any changes that may be pending. self.connection.close() self.db.close() self.st.close() When I open again and try verify whether the keys exist, using self.dbroot.has_key(CstNo) # for example they do not exist. Looking at the DB with a text editor to see what is in there, reveals that there is nothing. The entire program runs through without any error. HOWEVER, if I mark out the line: # self.dbroot = OOBTree() It all works according to plan !!! Does anybody have an idea what is wrong with my usage of the OOBTree ???