Spatial Hash for particle system broken

Hi all
I am making a spatial hash with for a particle system. One of the things required is to find neighboring particles, which is were the error is I believe. Anyway, it seems broken and not retriving the right neighbors and I cant really tell why. I would really appreciate any help here

Kind Regards

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using System.Linq;
5. 
   
6. public class SpatialHash {
7. 
   
8. Dictionary<int,List<Particle>> hash;//= new Dictionary<List<Particle>,int>();
9. public float cellSize;
10. public int max;
11. 
    
12. public SpatialHash(float cSize,int m)
13. {
14. hash = new Dictionary<int,List<Particle>>();
15. cellSize = cSize;
16. max = m;
17. }
18. 
    
19. public void AddParticleToHash(Particle nParticle, int key)
20. {
21. if(hash.ContainsKey(key))
22. hash[key].Add(nParticle);
23. else
24. {
25. hash.Add(key,new List<Particle>());
26. hash[key].Add(nParticle);
27. }
28. }
29. public void ClearGrid()
30. {
31. hash.Clear();
32. }
33. public int GetKey(Vector2 position)
34. {
35. return (int)(position.x/cellSize)*max +(int)(position.y/cellSize);
36. }
37. public List<Particle> getNeighbors(int key , int searchDistance , int capacity)
38. {
39. int x = (key/max);
40. int y = key - x*max;
41. 
    
42. List<Particle> temp = new List<Particle>();
44. 
    
45. for(int i = x - searchDistance; i <= x + searchDistance ;i++)
46. {
47. for(int j = y - searchDistance; j <= y + searchDistance ;j++)
48. {
49. int keyTemp = (i)*max +(j);
50. if(hash.ContainsKey(keyTemp))
51. {
52. temp.AddRange(hash[keyTemp]);
53. }
54. }
55. }
56. return temp;
57. }
58. 
    
59. }