Originally Posted by
ualboston1k
You may not get full credit if you book on a website where you cannot see the airline before booking the trip.
Example: Priceline or hotwire. They will show you a price, but not an airline or itinerary until after you purchase the ticket. These will not earn any miles.
Not only you don't earn any miles, but sometime they won't even allow you to stand by on earlier flights. I had this happened to me before.