Softimage Xsi: vortex force question

After applying a vortex force to a simple particle emitter, the particles, instead of vortexing, shoot of the screen at high speeds in apparently random directions. Adjusting the vortex amplitude and the particle's sensitivity to the field do nothing (apparently). Any suggestions?


Also, I just submitted this post 15 secs ago and it never showed up in the forum, so if it double posts, pardon my ignorance, and please delete the excess. Thanks.
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Poly Guru