Index not fully populated by Artist on Droid

[csoldfield]

When I connect via my Droid to my server, the top level list does not include all artists. However, I have an entry shown in the top level list that is the name of a directory, selecting that gives me what appears to be a directory listing of the sub folders. From there I can view/play the missing tracks.

What are the rules for allowing the indexing to properly create a full Artist populated index? Running latest Droid Subsonic version.