I've been reading a lot of articles on how to book a free one-way ticket using reward miles but I can't seem to do it myself. I was trying to book DTW-LAS MAY 15, LAS-DTW MAY 18, DTW-DCA JUNE 20. It comes up as 60,000 points. I'm trying to book a round trip to Las Vegas from Detroit (my hub) and then a future one way to DC. Is this not possible? What am I doing wrong?