Is that W and C don't base-pair. You know what works? Goldstein-Crick base pairing.
(Why this should be funny but probably isn't to you: In addition to the A, T, G, and C of normal DNA sequences, other letters of the alphabet are used to designate possiblities, e.g. W = weak, which could be either A or T, so named because they make only 2 hydrogen bonds, as compared to the Strong G-C base pairs which are held together by 3 bonds.)