By the way ... this seems to work without any problem:

Code:
STRING* cubeStr1 = "skycube04_high+6.tga";
STRING* cubeStr2 = "skycube07_high+6.tga";

ENTITY* cube = { 
	type="skycube04_high+6.tga";
	layer=2;       
	z=5;	
	flags2 = SKY | CUBE | SHOW;
}



void main() {		
	
	level_load("telescope_room.wmb");	
	
	int i = 0;
	
	while(1) {	
		
		wait(-5);
		
		if (i == 0) {
			i = 1;
			ent_morph(cube, cubeStr2);
		} else {
			i = 0;
			ent_morph(cube, cubeStr1);
		}
		
		wait(1);				
	}
	
}