Nest List DWR Client Side Problem

I have a java POJO/Object that consists of nested LIST (2 levels).  On the client side, using javascript, I always get an error when trying to get the innermost List.  That is, I can retrieve the outermost List easily, but when I go deeper and get the innermost List, I get an “ERROR” on the DWR test page.   Can someone give me an example on how to use nested LIST?

Tim