The DDE is valid from the date of issue so say May 06 - April 07, If you activate your AP voucher in Dec then that would be valid Dec 06 - Nov 07 they don't match. It is best to order the DDE as laste as possible
Don't know if this is still the case Jill, but when I got mine I ended up with slightly more than 12 months on it. I orderd on 1st August and the DDE expired at the August after so I had from 1st August 05 to 31st August 06. Nice bonus i you can work it that way