I can not confirm the UK100 problem here. Maybe somethign wrong with your UK100 data? You can test the AssetZone this way:

Code:
BarPeriod = 60;
FrameOffset = 9; // trade both assets at 9:00 of their local time
while(asset(loop("NAS100","UK100"))){ 
	if(strstr(Asset,"NAS100"))
		AssetZone = ET; 
	else if(strstr(Asset,"UK100")) 
		AssetZone = WET;
	TimeFrame = AssetFrame;
	if(frame(0))
		printf("\n%s %s",Asset,strdate(YMDHMS));
}