Submeshs doesn't combine with materials

Simple as that, submeshs doesn't combine with materials and i get an error: Failed setting triangles. Some indices are referencing out of bounds vertices. IndexCount: 18, VertexCount: 4.

The count of submesh is same count as material, i think the error is coming from this: All submeshs aren't assing yet with an material. How can i fix it? Don't give me all the solution, i hate that...

Here's the script!

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class ScreenBoard : MonoBehaviour {

 public Transform ScreenObject;
 //public Texture2D PixelsRed;
 //public Texture2D PixelsBlue;
 //public Texture2D PixelsGreen;
 //public Texture2D PixelsBlack;
 //public Texture2D PixelsWhite;
 //public Texture2D PixelsYellow;
 //public Texture2D PixelsOrange;
 //public Texture2D PixelsMangenta;

 public Material[] mats;

 List<Vector3> vertices;
 List<int> triangles;
 List<Vector2> uvs;

 MeshFilter mf;
 Mesh mesh;
 MeshRenderer mr;

 int[,] ColorIdInt;
 int ColorInt;

 //15w by 10h pixelscreen

 void ResetScreen() {
     vertices = new List<Vector3>();
     triangles = new List<int>();
     uvs = new List<Vector2>();

     ColorIdInt = new int[15,10];
     mf = ScreenObject.GetComponent<MeshFilter>();
     mesh = new Mesh();
     mr = ScreenObject.GetComponent<MeshRenderer>();
     mf.mesh = mesh;
     mesh.subMeshCount = 8;

 }

 void SetPixelUpdate(float X, float Y, string ColorId) {
     int SaveX = Mathf.RoundToInt(X);
     int SaveY = Mathf.RoundToInt(Y);
     X = Mathf.RoundToInt(X);
     Y = Mathf.RoundToInt(Y);
     X = X * 0.1f;
     Y = Y * 0.1f;

     Vector3[] verticles = new Vector3[4] {
         new Vector3(X + 0, Y + 0, -0.01f), new Vector3( X + 0.1f, Y + 0, -0.01f), new Vector3(X + 0, Y + 0.1f, -0.01f), new Vector3(X + 0.1f, Y + 0.1f, -0.01f)
     };

     int[] tri = new int[6];

     tri[0] = vertices.Count + 0;
     tri[1] = vertices.Count + 2;
     tri[2] = vertices.Count + 1;

     tri[3] = vertices.Count + 2;
     tri[4] = vertices.Count + 3;
     tri[5] = vertices.Count + 1;

     foreach(Vector3 V3 in verticles) {
         vertices.Add(V3);
     }
     foreach(int TS in tri) {
         triangles.Add(TS);
     }

     mesh.vertices = vertices.ToArray();
     mesh.triangles = triangles.ToArray();

     Vector2[] uv = new Vector2[4];

     uv[0] = new Vector2(0,0);
     uv[1] = new Vector2(1,0);
     uv[2] = new Vector2(0,1);
     uv[3] = new Vector2(1,1);

     foreach(Vector2 SingleUV in uv) {
         uvs.Add(SingleUV);
     }

     mesh.uv = uvs.ToArray();
     mesh.RecalculateNormals();

     ColorInt = 0;

     switch(ColorId) {
         case "Red":
             ColorInt = 0;
         ColorIdInt[SaveX,SaveY] = 1;
             break;
         case "Green":
             ColorInt = 1;
         ColorIdInt[SaveX,SaveY] = 2;
             break;
         case "Blue":
             ColorInt = 2;
         ColorIdInt[SaveX,SaveY] = 3;
             break;
         case "Black":
             ColorInt = 3;
         ColorIdInt[SaveX,SaveY] = 4;
             break;
         case "White":
             ColorInt = 4;
         ColorIdInt[SaveX,SaveY] = 5;
             break;
         case "Yellow":
             ColorInt = 5;
         ColorIdInt[SaveX,SaveY] = 6;
             break;
         case "Orange":
             ColorInt = 6;
         ColorIdInt[SaveX,SaveY] = 7;
             break;
         case "Magenta":
             ColorInt = 7;
         ColorIdInt[SaveX,SaveY] = 8;
             break;
         default:
             ColorInt = 0;
         ColorIdInt[SaveX,SaveY] = 1;
             break;
     }
     mesh.subMeshCount = 8;
     mf.mesh.SetTriangles(triangles, ColorInt); //ColorInt > submesh
     mr.materials = mats;
 }

 void Fill (int X1, int Y1, int X2, int Y2, string ColorId) {
     for(int x = 0; x < X2; x++) {
         for(int y = 0; y < Y2; y++) {
             SetPixelUpdate(x + X1, y + Y1, ColorId);
         }
     }
 }

 int GetColorOnPixel (int X, int Y) {
     if(ColorIdInt[X,Y] != null) {
         return ColorIdInt[X,Y];
     } else {
         return 0;
     }
 }

 void RemovePixel (int X, int Y) {
     //new Vector3(X + 0, Y + 0, -0.01f), new Vector3( X + 0.1f, Y + 0, -0.01f), new Vector3(X + 0, Y + 0.1f, -0.01f), new Vector3(X + 0.1f, Y + 0.1f, -0.01f)
     vertices.Remove(new Vector3(X + 0, Y + 0, -0.01f));
     vertices.Remove(new Vector3(X + 0.1f, Y + 0, -0.01f));
     vertices.Remove(new Vector3(X + 0, Y + 0.1f, -0.01f));
     vertices.Remove(new Vector3(X + 0.1f, Y + 0.1f, -0.01f));

     mesh.vertices = vertices.ToArray();

     ColorIdInt[X,Y] = 0;
 }

 // Use this for initialization
 void Start () {
     ResetScreen();
     SetPixelUpdate(1,1, "Red");
     SetPixelUpdate(1,2, "Blue");
     SetPixelUpdate(1,3, "Green");

 }
 
 // Update is called once per frame
 void Update () {

 }
 }

I hope you understand; "bad english".