Why isn't B&N taking books from Simon & Schuster?

On January 30th, subscribers to Publishers Weekly’s email newsletter received a special “News Alert” with a red rectangle across the top. “Simon & Schuster, Barnes & Noble in Dispute Over Terms” the headline declared. But the message itself was cryptic, offering no details about the terms involved or a clear explanation as to why there was a dispute to begin with. PW managed to get one quote from a B&N spokesperson: