I have an Apple Airport Express unit attached my stereo system, and I use the iTunes Remote app on my iPad to play music that is stored in iTunes on a Mac mini. This usually works great, but I noticed a problem after cleaning up my music library: some albums would not play all of their tracks in sequence.
Usually, when you tap the first track of an album in the iTunes Remote app, all of the songs on that album will be queued and will play in order. But several albums in my library would only play the first track, then stop. I could tap to start the second track, but then the third track would not play.
After A/B testing different settings in two different iTunes libraries, I discovered the problem. Every track in the iTunes library has a "checkbox" next to it that you can see in the song list view. Normally, that checkbox is used to indicate songs that can be synced to an iPod/iPhone. But if the songs are unchecked, they are also not queued by default when played via iTunes Remote.
After setting the checkbox on all of the songs in my library, every album now plays sequential tracks as expected. I'm not sure why some albums were unchecked by default, and I have yet to find any Apple documentation on this feature. So this will be something I watch as I add new music.