[SQLObject] Please help...

Can anyone please hint me where to start fixing this? I've spent
day's on this problem...

I have got a list with objects:

p = [<Person 1 lastname=u'Koen' firstname=u'Harry'>, <Person 2
lastname=u'Hei' firstname=u'Yvin'>, <Person 3 lastname=u'Stoop'
firstname=u'Dirk'>, <Person 4 lastname=u'Dooijes'
firstname=u'Ciaran'>, <Person 5 lastname=u'Ensink' firstname=u'Anneke'>]

I am feeding this list to an NSArrayController, and displaying it in
an NSTableView. It works, but for each key I get such an error in the
console:

2005-09-05 12:14:07.657 Etalage[317] *** Ignoring ***
addObserver:forKeyPath:options:context: for 'lastname' (of
<NSArrayController: 0x119daa0>[object class: NSMutableDictionary,
number of selected objects: 1] with 0 in 0x0).