As BigBambi said that's a fairly old build. I first thought something else was wrong for you because I expected you would use a current build (as the forum guidelines you agreed on when joining require you to

hint).
Anyways, do you have "gather runtime data" enabled? It's only briefly covered in the manual but you need to enable this option in order to get "recently added" (and the others) working. Searching in the forums and especially the wiki brings up some useful information (pointing to the guidelines again...).
My first thought was that it is related to what's described in this bug report (
FS#8040 - Gather Runtime Data stopped working with r15306). I don't use this feature so don't know if it has been fixed already, please update, try and report back.