Sometimes when I animate the strength of some sort of lamp or material, the keyframes for it appear in the dopesheet. This is useful especially when using the "display selected only" button. It makes it precise and clear to see what I am doing while animating.
Sometimes they appear in the dopesheet, but NOT with the selected mode. This is annoying, for I have to search the keyframes in huge amounts of channels and stuff. Almost impossible to work that way.
And sometimes they don't appear at all. Which is ... I don't have words :)
It might also happen, that they first appear, and after changing something (I have no Idea what) I can't use the 'selected only' tag anymore.