[addon question] rare spawns

morning,

i googled/downloaded 3 versions of NPC_Scan that should be working,they show up up under addons and are not outdated according to screen..but they dont do anything. literally.
i ran head first into a rare earlier..and got nothing.

could someone point me the way to the "NPC_Scan" addon that is confirmed working on this servers version? (Lordaeron)
or alternatively point out an addon that does the same aka alert you to the presence of a rare spawn near you etc?

thanks

anyone? please?