Some Prefabs are not Loading

I am using six prefabs right now: Cross, Straight, Curve, End, Tee, Blank. All of them load and are able to be instantiated, except for End and Tee, which when I try to instantiate either, give the error “ArgumentException: The prefab you want to instantiate is null.”

I load everything here:

		public GameObject fabCross_Tile = Resources.Load("Cross") as GameObject;
		public GameObject fabStraight_Tile = Resources.Load("Straight") as GameObject;
		public GameObject fabCurve_Tile = Resources.Load("Curve") as GameObject;
		public GameObject fabEnd_Tile = Resources.Load("End") as GameObject;
	    public GameObject fabTee_Tile = Resources.Load("Tee") as GameObject;
		public GameObject fabBlank_Tile = Resources.Load("Blank") as GameObject;

I initialize everything here:

		public void initialize_cross ()
		{
			entity = fabCross_Tile;
			t_top = 1;
			t_right = 1;
			t_bottom = 1;
			t_left = 1;

			print (entity);
		}

		public void initialize_straight ()
		{
			entity = fabStraight_Tile;
			t_top = 1;
			t_right = -1;
			t_bottom = 1;
			t_left = -1;

			print (entity);
		}

		public void initialize_curve ()
		{
			entity = fabCurve_Tile;
			t_top = 1;
			t_right = -1;
			t_bottom = -1;
			t_left = 1;

			print (entity);
		}

		public void initialize_end ()
		{
			entity = fabEnd_Tile;
			t_top = 1;
			t_right = -1;
			t_bottom = -1;
			t_left = -1;

			print (entity);
		}
		
		public void initialize_tee ()
		{
			entity = fabTee_Tile;
			t_top = 1;
			t_right = 1;
			t_bottom = -1;
			t_left = 1;

			print (entity);
		}

		public void initialize_blank ()
		{
			entity = fabBlank_Tile;
			t_top = -1;
			t_right = -1;
			t_bottom = -1;
			t_left = -1;

			print (entity);
		}

At this point, it prints out Null for End and Tee, but the correct values for everything else.

are these prefabs well named in the resources folder ?