[osflash] duplication problem

[bardo]

hi all , im trying to duplicate a dynamic sprite , but im getting 
frustrated.
I have experimented with 2 methods mainly , senocular's 
duplicateDisplayObject and this one

            var originalItem:Object = obj;//
            var itemClass:Class = originalItem.constructor;
            var itemo:* = new itemClass();


but all two seems to works only with sprites or movies i embed from an 
swf compiled in flash(but im a flex user) , but no one seems to works 
with sprites created dynamically.Any suggestion?
tnx in advice
Davide Arcinotti