Softimage Xsi: Lighting/association problems

Hi, i'm new to XSI, and this is my first attempt at a short animation. I'm trying to achieve a sharp crisp shadow cast by the ant with an infinite light, and a soft-edged shadow cast by the body of the car with a point light.





Unfortunately the ant appears to be casting shadow from the point light, even though it's associated with that light, and the light is set to exclusive. Tests in another scene showed that objects excluded from a light should not cast shadows...which makes perfect sense.





Another strange thing is, the undesirable shadow that's being cast is mostly soft, but has a clean edge at the back. Very odd.


I'm hoping i've made an elementary error here and someone can set me straight.


Any feedback on the matter would be much appreciated.