AS3 unfair to noob using nested movieclips

In my ongoing quest to learn AS3 I am rewriting some of the many, many interactives I have done in AS2. There have been several AS2 interactives where I have used a map of California. The map itself is a movieclip and within that movieclip, all the counties are movieclips that function as buttons and above the counties are the county names which are also movieclips. In other words when you mouse over the counties they do things; the most simple being the county name alpha goes from 0 to 1. In AS2 all the movieclips respond to roll overs even though they are physically obscured by other movieclips within the main map movieclip. In AS3 the county movieclips (which are on the lowest layer within the main map movieclip) are obscured by other movieclips on higher layers and do not respond to Roll Overs etc. When I move the county movieclips to the highest layer within the main map movieclip, they work just fine. Of course then they obscure all the map details such as roads, labels, etc.

Is there some setting to allow movieclips to be read through other movieclips that are physically above them within a main movieclip.