setSortOrderings?

Hola amigos!

I am trying to sort the contents of a displayGroup; I'd try the 
following

EOSortOrdernig = 
NSClassFromString(@"com.webobjects.eocontrol.EOSortOrdering");
EODisplayGroup* dg; //suppose this exists

[dg setSortORdering:[NSArray arrayWithObject:[EOSortOrdering 
sortOrderingWithKey:@"detalle" :@selector(CompareDescending)]]];

it does not work.... worse than that: the app exists with signal 11 
(SIGSEGV)

Any clue???

I think that the problem is with the @selector(CompareDescending) but I 
do not know how to jump the Java-Bridge with such a kind of paramater.
PLS HELP

(I am using OSX 10.2.3 and WO 5.2 ---previous to december relase---)

Dino
http://homepage.mac.com/strausz