button (0, 0, "test.tga", "test.tga", "test_light.tga", NULL , NULL, NULL);
Here you had to define an function which shall be called when pressing the button. define this, and your button should work.
That's not his problem. His problem is that when he hovers over the button, that it doesn't change to the 'bmap_over' image.
I know it might sound dumb but double check your files again just to make sure that 'over' image isn't in fact a copy of the 'off' image.
To see if it's a mouse problem, set mouse_mode to 4 rather than 2, and remove the stuff afterwards like 'mouse_pos.x = mouse_cursor.x'.
