Mesh don't receive shadow correctly

Hi to every one. A got a problem and I have no Idea how to correct it.
So in my scene I use a hemispheric light and a spot light, I enabled shadows in all possible places, camera, light, and meshes(by traversing my .fbx model). And as you can see in pictures bellow problem with shadows appears only on vertical surfaces, on grass everything is ok. I guess this myght be a problem in the model, but I’m not artist, so if there is something that I can do to get rid of this bug, please tell me. Thanks to every one who replay!!!

There I set all my lights:
export function initScene(){

const scene = new THREE.Scene();

// scene.fog = new THREE.Fog('FFFFFF', 20, 500);

//Add Light

let hemiLight = new THREE.HemisphereLight(0x89b2d3, 0x696559, 0.8);
scene.add(hemiLight);


let spotLight = new THREE.SpotLight(0xffa95c, 0.5);
spotLight.angle = Math.PI / 40;
spotLight.shadow.bais = -0.00001;
spotLight.shadow.mapSize.width = 1024 * 16
spotLight.shadow.mapSize.height = 1024 * 16
spotLight.position.set(100, 300, 100);
spotLight.rotation.x = 90;
spotLight.castShadow = true;


spotLight.shadow.mapSize.width = 512;
spotLight.shadow.mapSize.height = 512;

spotLight.shadow.camera.near = 0.5;
spotLight.shadow.camera.far = 500;
spotLight.shadow.camera.fov = 30;


spotLight.target.position.set( 0, 0, 0 );
scene.add( spotLight.target );

scene.add(spotLight);

var lightHelper = new THREE.SpotLightHelper( spotLight );
scene.add( lightHelper );


var helper = new THREE.CameraHelper( spotLight.shadow.camera );
// scene.add( helper );


initSky(scene)

return scene;

}

There are results