Create new mesh from script always black color even i change material.

Hi everyone who read this post.

I am using 2019.3.0b1 with URP.

I have problem that my mesh which i created from script always show black color even i change material.

this is my script very simple to create single triangle

 public class DrawMeshManager : MonoBehaviour
 {
     // Start is called before the first frame update
     void Start()
     {
         DrawMesh();
 
     }
 
     private void DrawMesh()
     {
         Mesh mesh = new Mesh();
 
         Vector3[] vertices = new Vector3[3];
         Vector2[] uv = new Vector2[3];
         int[] triangles = new int[3];
 
         vertices[0] = new Vector3(0, 0);
         vertices[1] = new Vector3(0, 100);
         vertices[2] = new Vector3(100,100);
 
         uv[0] = new Vector2(0,0);
         uv[1] = new Vector2(0,1);
         uv[2] = new Vector2(1,1);
 
         triangles[0] = 0;
         triangles[1] = 1;
         triangles[2] = 2;
 
         mesh.vertices = vertices;
         mesh.uv = uv;
         mesh.triangles = triangles;
 
         GetComponent<MeshFilter>().mesh = mesh;
     }
 
     // Update is called once per frame
     void Update()
     {
         
     }
 }

This is what i look after create mesh from script. As you can see that my mesh is completely black

And this is information of my materials.

Please help me my problem. Thank you.