Can't get started - GMS error

Hey guys, I've just tried to do the getting started part of this website, and am getting this error:


___________________________________________
###############################################
FATAL ERROR in
action number 1
of Create Event
for object obj_GMS:

Variable obj_GMS.GMS(100011, -2147483648) not set before reading it.
at gml_Object_obj_GMS_CreateEvent_1 (line 1) - gms_init(GMS);
###############################################

Any ideas?

Thank you.

EDIT: Never mind, I named my GMS object obj_GMS and had to use that in the parameter for gms_init() instead of GMS.