How to access light shader information of 3ds Max

[toshi]

Hello,

I want to get directional light shader information of 3ds max.
I defined light shader structure like below in my surface shader.

struct MaxDirectionalLight {
	struct GeneralParameters {
		miBoolean On;
		miColor Color;
		miScalar Multiplier;
		miScalar Contrast;
		miScalar SoftenDiffuseEdge;
		miBoolean AffectDiffuse;
		miBoolean AffectSpecular;
		miBoolean AmbientOnly;	
	} generalParameters;
	struct DirectionalParameters {
		miScalar HotSpot;
		miScalar Falloff;
		miInteger Overshoot;
		miInteger Shape;
		miScalar Aspect;		
	} directionalParameters;
	struct AttenuationParameters {
		miBoolean UseNearAttenuation;
		miScalar NearStart;
		miScalar NearEnd;
		miBoolean UseFarAttenuation;
		miScalar FarStart;
		miScalar FarEnd;
		miInteger Decay;
		miScalar DecayRadius;
	} attenuationParameters;
	struct ShadowParameters {
		miBoolean CastShadows;
		miColor ShadowColor;
		miScalar ShadowDensity;
		miBoolean ShadowAffected;
		miBoolean UseShadowProjector;
		miTag ShadowProjector;
	} shadowParameters;
	struct ProjectorParameters {
		miBoolean UseProjector;
		miTag Projector;
	} projectorParameters;
	struct AtmosphericShadows {
		miBoolean AtmospheresCastShadows;
		miScalar ShadowOpacity;
		miScalar ShadowAmount;
	} atmosphericShadows;
	struct LightIncludeExclude {
		int     i_exclusionList;
		int     n_exclusionList;
		miTag	exclusionList[1];
	} lightIncludeExclude;
};

I attempted to access this way to shader information.

		
miTag realLight, shaderTag, shaderName;
MaxDirectionalLight* dirLightData;
mi_query(miQ_INST_ITEM, NULL, *light, &realLight);
mi_query(miQ_LIGHT_SHADER, state, realLight, &shaderTag );
mi_query(miQ_FUNC_PARAM, state, shaderTag, &dirLightData);

But could not to get dirLightData.

Could you tell me how to get light shader information of 3ds Max from surface shader?