2012 trees and people not rendering

Just got new pc and rendering isn't working correctly on Revit 2012. So far trees, shrubs, and people do not render correctly. They come in as gray box, then when rendering, completely dissapear. I don't know if it's because they are RPC objects or something else. I added the folder location on the rendering tab but still doesn't work. Any suggestions?

you need to add the link to the RPC license manager, its located under the add library path tabs under the rendering tab of the options dialog box.