Goals are not part of the Nucleus architecture. When you create goals, you must compensate for the Nucleus wind and gravity that compete for control of the nParticle object. If you want your nParticles to reach a goal exactly, turn on the Ignore Solver Wind and Ignore Solver Gravity attributes on the nParticleShape node. If you don't need your nParticles to reach the goal exactly, or if you like the look of the particles working against wind or gravity while trying to reach the goal, leave Ignore Solver Wind and Ignore Solver Gravity off. See nParticle Dynamic Properties.