Failed setting triangles in my mesh

So, I'm trying to create an automated "Face Creator" for my Mesh, so I can just call a function, to create a face in a specific position, and height/width.

But I'm getting the error: Failed setting triangles. The number of supplied triangle indices must be a multiple of 3.

Which is weird, because I am actually using 6 ints, for the 2 triangles that a face have.

This is my code;

 using UnityEngine;
 using System.Collections;
 
 public class RoomCreator : MonoBehaviour {

 private Vector3[] Mesh_Vertices;
 private Vector2[] Mesh_Uvs;
 private int[] Mesh_Triangles;

 private MeshFilter meshFilter;

 void Start() {
     firstFace = true;

     Mesh_Vertices = new Vector3[100];
     Mesh_Uvs = new Vector2[100];
     Mesh_Triangles = new int[100];

     meshFilter = GetComponent<MeshFilter>();

     CreateRoom();
 }

 private void CreateRoom() {
     meshFilter.mesh = CreateMesh();
 }

 private Mesh CreateMesh() {
     Mesh m = new Mesh();
     m.name = gameObject.name + "_Mesh";

     CreateFace(new Vector3(0,0,0), 1,1);

     m.vertices = Mesh_Vertices;
     m.triangles = Mesh_Triangles;
     m.uv = Mesh_Uvs;
     m.RecalculateNormals();

     return m;
 }

 private void CreateFace(Vector3 position,int width, int height) {
     Mesh_Vertices[0] = new Vector3(position.x, position.y, 0);
     Mesh_Vertices[1] = new Vector3(position.x + width, position.y, 0);
     Mesh_Vertices[2] = new Vector3(position.x + width, position.y + height, 0);
     Mesh_Vertices[3] = new Vector3(position.x, position.y + height, 0);

     Mesh_Triangles[0] = 0;
     Mesh_Triangles[1] = 1;
     Mesh_Triangles[2] = 2;

     Mesh_Triangles[3] = 0;
     Mesh_Triangles[4] = 2;
     Mesh_Triangles[5] = 3;

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

}