Resources.Load returns null,Resources.Load don't load sprite

Questions & Answers
1

With this usage, the sprite does not change:

public void SetCubeType(string cT)
	{
		cubeType = cT;
		gameObject.GetComponent <SpriteRenderer> ().sprite = Resources.Load <Sprite> ("Sprites/Cubes/" + cubeType);
	}

but this works good

gameObject.GetComponent <SpriteRenderer> ().sprite = Resources.Load <Sprite> ("Sprites/Cubes/Fire");

If I check the value of “cubeType” through Debug.Log() it is equal to “Fire”
What’s wrong?

2

So I had same issue for my program. For me helped to make file name all letters lower case using method :
.ToLower()

cubeType = cT;
string cubeTypeFinalName = cubeType.ToLower();
         gameObject.GetComponent <SpriteRenderer> ().sprite = Resources.Load <Sprite> ("Sprites/Cubes/" + cubeTypeFinalName);