Need an answer about mcmmo

I would put this on the Dev site but it can take up to DAYS to get a response on the Dev site unlike when it use to be on these forums and you could get an answer that day and many times within the hour.

My question is: Why is it that if you sit near a spawner killing mobs that come out of it that you get no EXP towards your weapon? Do you have to wait a sertian amount of time before killing them to get exp or is it a certain distance that the mob has to travle away from it for it to give you exp?

If notch wouldn't have broken mob spawn rate and agro range I wouldn't need to camp a spawner to get a LOT of mobs to kill.