LIGHT_ATTENUATION problem

Hello, i''m making a 3D scene, with a light at the center. Given that i want a "nice light" (sorry for my english i''m french) i use LIGHT_ATTENUATION function but it doesn''t work !! I tried 0.000001 and 9999999999999 for the paramater, i always have the same result. And obviously, it''s a positional light. Can someone help me? Thank you. nullspace@vraifauxrum.com