Aha, CONSTANT instead of CONST.. I was wondering why that didn't work

I had the same problem, I had already created a program with the demo version but in a newer version it didn't compile because of the CONST' s. I use it a lot for defining things like "direction-enumeration" and gameobjects, for example.
CONSTANT DIR_UP = 1
CONSTANT DIR_DOWN = 2
// etc.
CONSTANT GAMEOBJ_NONE = 0
CONSTANT GAMEOBJ_WALL = 1
CONSTANT GAMEOBJ_LADDER = 2
// etc.
I assume GLBasic translates that to #defines in the C++ files, right?
#DEFINE GAMEOBJ_NONE = 0
#DEFINE GAMEOBJ_WALL = 1
#DEFINE GAMEOBJ_LADDER = 2
// etc.
Occasionally it won't compile? Do you mean when there is a naming conflict or something? For example, when you use a CONSTANT with the same name as a global/local variable or as a function name?