it's not an action.. its an event. it's under System
it sounds like you need to use it as a "sub-event"
I can't tell what you are trying to do.. but it should be something like this
CHECK the RANGE in a top level event like this:
if range < 200
(add a sub_event of this check) System Pick Nearest sprite etc... then add an action once you pick the nearest sprite...
it's not a system event or condition, pick nearest is an object event/condition..
so you don't use system pick nearest, but sprite pick nearest to a specific point..