NullReferenceException: Object reference not set to an instance of an object (int[,])

Hello, I am making simple game where I need to use two dimensional array, so I am using int[,].

Then on the scene load I am assigning values like this:

//GameBoardController.js
function getMatrix(){
  for (var i = 0; i < numrows; ++i){
    var columns: Array = [];
      for (var j = 0; j < numcols; ++j){
        activeCells[i,j] = 0;
      }
    }
  }
}

When I print print(activeCells) now, i get System.Int32[,] which is expected result.

But then in another function which is triggered by button:
84265-screenshot-from-2016-12-17-15-34-49.png

//GameBoardController.js
function resetScene(){
  for(var x = 0 ; x < sizeX ; x++){ //sizeX is as public int variable
    for(var y = 0 ; y < sizeY ; y++){ //sizeY is as public int variable
      activeCells[x,y] = 0;
    }
  }
}

And here is the problem. Function resetScene() is failing and giving me error message:

NullReferenceException: Object reference not set to an instance of an object
GameBoardController.resetScene () (at Assets/Scripts/GameBoardController.js:834)

But this is wrong because in the same script few lines above resetScene() I am assigning and then printing activeCells and everything is working.

Does please anyone know what am I doing wrong? Should I attach another GameBoardController script to the button? GameBoardController is attached to empty GameObject and everything but this works.

Nevermind, I had old controller (old GameObject with GameBoardController deactivated) assigned in the button. What a mystery :confused: