Nonadditivity of Bipartite Distillable Entanglement follows from   Conjecture on Bound Entangled Werner States
  Assuming the validity of a conjecture in quant-ph/9910026 and quant-ph/9910022 we show that the distillable entanglement for two bipartite states, each of which individually has zero distillable entanglement, can be nonzero. We show that this also implies that the distillable entanglement is not a convex function. Our example consists of the tensor product of a bound entangled state based on an unextendible product basis with a Werner state which lies in the class of conjectured undistillable states. 
Peter W. Shor, John A. Smolin and Barbara M. Terhal