Not sure why it isn't working for you. Well, there's always the old-fashioned way. Using either Poser or a text editor, figure out which texture map goes with each material. Unless....could this barn use proceedurals? Was it a Poser5 only item? The other way to go is with Carrara's own materials. Check out the Lumber Yard shaders some time. Not quite a weathered wood, but you should be able to get there...