Gtkmm deriving (extending) TreeView

I am trying to extend TreeView like this:

class FileList : public Gtk::TreeView{
public:
FileList();
FileList(BaseObjectType* cobject, const Glib::RefPtr<Glade::Xml>&
refGlade);
virtual ~FileList();

class ColumnModel : TreeModel::ColumnRecord{
public:
ColumnModel(){
add(nameCol);
add(sizeCol);
}

TreeModelColumn<ustring> nameCol;
TreeModelColumn<int> sizeCol;
};

ColumnModel columns;
};

Later I try and get a TreeView from an already initialized glade file,
like this:

FileList* list = NULL;
xml->get_widget_derived("files_tree", list);

It won;t compile saying that there is an undefined reference to
'typeinfo for FileList' in xml.h (from get_derived_widget).

Did I miss something?

.