Problem with "room_goto"

[JapanGamer29]

I have a problem with my rooms.

Room 1 - a start menu with a button to jump to Room 2
Room 2 - the game

If I only run Room 2, or put it ahead of Room 1 in the resource tree, it works as expected. However, if Room 1 is the first room then I get this error after jumping to Room 2:

Variable references invalid object

Why would Room 2 only throw this error after the room_goto action in Room 1, and not when run independently. Is it something to do with persitence? Or is Room 1 not finished before Room 2 starts? I'm very confused. Anyway, here's the actual code:

ROOM 1 START MENU

switch (mpos)
{
	case 0:
		room_goto(rm_board); // rm_board is Room 2 
		break;
	case 1:
		room_goto(rm_options);
		break;
	case 2:
		game_end();
		break;
	default:
		break;
}

ROOM 2 - which contains a "controller" object with this Create event:

globalvar grid;

grid = instance_create_layer(0, 0, rm_board, obj_grid);

// grid object
grid.xs = 60;	
grid.ys = 30;

ERROR

FATAL ERROR in
action number 1
of Create Event
for object obj_controller:

Pop :: Execution Error - Variable references invalid object (-4).<unknown variable>
 at gml_Object_obj_controller_Create_0 (line 14) - grid.xs = 60;  

Any help is much appreciated.

[Thew]

The issue is you're passing a resource name (a room) to the instance_create_layer() function. It's looking for a layer ID, typically in quotes.

instance_create_layer(0, 0, "Layer_Name", obj_grid);

Here's the function reference from the manual:
https://docs2.yoyogames.com/source/_build/3_scripting/4_gml_reference/instances/instance_functions/instance_create_layer.html

Hopefully this will fix your problem!

[Wardiaper]

The only thing I see is your controller create event line: grid = instance_create_layer(0, 0, rm_board, obj_grid);

Shouldn't the "rm_board" be a layer - something like "Instances" with the quotes included? (if you really meant to use "instance_create_layer" instead of something like mp_grid_create - unless that is created in your obj_grid object.)

Edit - oops, Thew got you already.

[JapanGamer29]

Brilliant! That was it. Thank you both very much. :-)