You should do a distance check then, much simpler. Use System's "Pick by comparison", select object "waste barrel", distance(Dexter.X, Dexter.Y, barrel.X, barrel.Y), comparison <= 30. If the picking operation select at least one barrel, it'll execute the actions.
Moreover, instead of the wait 0.4 second, you should add a "every 0.4 second", I believe that will behave more like you intended.