Dynamicly add Gameobjects for use

I really try to work these things out myself but being new to coding in Unity this one has stumped me for a couple of days. Here is the code I have:

for( int i = 0; i < puzzleTiles; i++ )
		{
			Debug.Log("Working On ID: " + i);
			newBricks _= (GameObject)Instantiate(Brick, locations*, Quaternion.identity);*_

_ GameBlocks.Add(i++, newBricks*);
}
The prefab it is using is a scripted gameobject but I keep getting this error with this code:
NullReferenceException: Object reference not set to an instance of an object
GMEncounter.Start () (at Assets/Scripts/GMEncounter.cs:82)
Thanks for any input.
-Alexander*_

One of the four objects being used is null. newBricks, Brick, locations or GameBlocks.

Use a debugger to catch the exception and then use watches to see whats null, or add null checks on each of them that prints out an error to see which is null.