I get a crash in ent_loacseconduvset(e3, e4), each mesh has 1870 faces.. any ideas?

Code:

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var video_mode = 8;

plugindir = ".";
dllfunction ent_exportmesh(entity, filename);
dllfunction ent_importmesh(entity, filename);
dllfunction ent_loadseconduvset(entity1, entity2);



//----------------------------------------------------------------------------- mtl_lightmap
bmap bmap_lightmap = "lightmap.dds";
bmap bmap_plantlightmap = "tower_lightmap.dds";

material mtl_lightmap
{
	skin1 = bmap_lightmap;
	
	effect=
	"
	texture mtlSkin1;
	texture entSkin1;

	technique t0
	{
		pass p0
		{
			Texture[0]=<mtlSkin1>;
			Texture[1]=<entSkin1>;
			
			// mix light map with dynamic lighting 
			TexCoordIndex[0] = 1;
			ColorArg1[0] = Texture;
			ColorOp[0] = AddSigned;
			ColorArg2[0] = Diffuse;
			
			// apply lighting to texture
			TexCoordIndex[1] = 0;
			ColorArg1[1] = Texture;
			ColorOp[1] = Modulate2x;
			ColorArg2[1] = Current;
		}
	}
	";
}


material mtl_plantlightmap
{
	skin1 = bmap_plantlightmap;
	
	effect=
	"
	texture mtlSkin1;
	texture entSkin1;

	technique t0
	{
		pass p0
		{
			Texture[0]=<mtlSkin1>;
			Texture[1]=<entSkin1>;
			
			// mix light map with dynamic lighting 
			TexCoordIndex[0] = 1;
			ColorArg1[0] = Texture;
			ColorOp[0] = AddSigned;
			ColorArg2[0] = Diffuse;
			
			// apply lighting to texture
			TexCoordIndex[1] = 0;
			ColorArg1[1] = Texture;
			ColorOp[1] = Modulate2x;
			ColorArg2[1] = Current;
		}
	}
	";
}


//----------------------------------------------------------------------------- main
entity* e1;
entity* e2;

entity* e3;
entity* e4;

function main()
{
	wait(3);
	level_load("empty.wmb");
	wait(1);
	
	vec_set(sky_color, vector(250, 175, 75));
	
	vec_set(sun_angle, vector(160, -35, 0));
	sun_light = 20;
	
	vec_set(camera.x, vector(300, 0, 200));
	camera.pan = 180;


	
//	// example 1
//	
	// load model with texture uv-set
	e1 = ent_create("landscape.mdl", nullvector, 0);
	e1.material = mtl_lightmap;
	
	// load model with light map uv-set	
	e2 = ent_create("landscape_lm.mdl", nullvector, 0);
	
	// generate and assign a new mesh with both uv-sets
	ent_loadseconduvset(e1, e2);
	ent_remove(e2);
	
	// save mesh with both uv-sets for faster reuse
	ent_exportmesh(e1, "landscape_lm.mesh");
	
	////////////////////////
	
	e3 = ent_create("plant.mdl", nullvector, 0);
	e3.material = mtl_plantlightmap;
	
	// load model with light map uv-set	
	e4 = ent_create("plant_lm.mdl", nullvector, 0);
	
	// generate and assign a new mesh with both uv-sets
	ent_loadseconduvset(e3, e4);
	ent_remove(e4);
	
	// save mesh with both uv-sets for faster reuse
	ent_exportmesh(e3, "plant_lm.mesh");

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