Help Android Desire: Why does the music app not recognize MP3s in certain subfolders?

[mmoser]

I am using the vanilla Music app that came with my HTC Desire. In principle it fulfills all my needs but there is one thing that's increasingly puzzling and annoying me: I also started to copy misc. podcasts over to the HTC and I would like to keep those files in a common subfolder "Podcasts". However, when I move those MP3s into such a folder HTC_DESIRE:\MP3\Podcasts\<podcastname>\<filename>.mp3 they are not listed any more in the Music app. If I move them one level higher into HTC_DESIRE:\MP3\<podcastname>\<filename>.mp3 then they appear and can be played.
But strange enough, all my other MP3s are located on similarly "deep" levels, namely: HTC_DESIRE:\MP3\<artist>\<album>\<songname>.mp3.
Any idea, what could cause the files in the Podcasts-subdirectory to not be shown?

Hope, I could make myself clear...