I have 408,000 sky miles and want to buy 450,000 miles worth of tickets using the "Miles and cash" option. So I search for my flights and click the "Miles and Cash" option, and continue. Everything works fine until I confirm the return flight on my reservation. For a moment it shows the amount of cash differential I owe, but then I t get this message: "We’re sorry, your balance of 408,643 Miles is not enough to redeem this Award Ticket." I have no choice but to return to the beginning. How come "miles and cash" doesn't work? Is there a way to make it work property?