It's also possible that the layer was not set to be visible (if I remember right that's an option)

The not showing up thing is annoying, the thing I have found, especially in Naboo, is they didn't name everything but if you get rid of the + in the bottom left side of the object window where is say containing. Pressing CLR does this, all the prevoiusly not listed object appear on the list. They still don't have a name on the left side but their ODF name shows up on the right side.

And it is a Teancum mentioned the show layer for the base layer is off. To change it to show choose Change under Active layer. Right click on base and click the show square. Then you get a huge forest but you can't see it because of the trees Okay sorry bad joke.

BTW getting back on topic are we getting anywhere in solving the problem you were having?