Thank you again for the post.
As said in the other post ( viewtopic.php?f=23&t=641
) we are in the process at the moment for updating the truss tool and improving its features as well as adding many more tools.
What you can do for now is to draw your own truss using sketchup native tools and use the PlusSpec BIM tool to add BIM properties. You can then go and add the material from the PlusSpec trusses to your truss and everything will work fine.