How to array?

Hopefully a simple question, I have a prefab with a script. Inside the script I have a variable:

public MovementTypes[,] Movement;

MovementTypes is an enum.

In an Editor script, I have

		for (int y = 0; y < 5; y++)
		{
			EditorGUILayout.BeginHorizontal ();
			for (int x = 0; x < 5; x++)
				myPieceType.Movement[x,y] = (PieceType.MovementTypes)EditorGUILayout.EnumPopup(myPieceType.Movement[x,y]);
			EditorGUILayout.EndHorizontal ();
		}

It works when Movement is not an array. As an array, it throws lots of NullReferenceExceptions. How do I make this work?

You have to intialize your array.

public MovementTypes[,] Movement = new MovementTypes[5,5];