Are you sure that you are running the correct script? You can tell from the Preferences window. In SED there also is a checkbox which if enabled will run the current active script in the script editor. Here is what I do to load a simple model and attach function to it with Lite-c Pure Code:

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#define PRAGMA_PATH "%EXE_DIR%\templates\models";

#include <acknex.h>

ENTITY* gsmodel;

void rotate_cube()
{
	while(1)
	{
		my.pan +=3*time_step;
		my.roll +=3*time_step;
		wait(1);
	}
}

void main()
{
	level_load(NULL);
	gsmodel = ent_create("cube.mdl",vector(0,0,0),rotate_cube);
	
	while(1)
	{
		camera.x = -100;
		camera.y = 0;
		wait(1);
	}
}

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