Newly acquired defensive tackle Darwin Walker won't report to the Bills until he receives a contract extension. Acquired in a trade in March that sent linebacker Takeo Spikes to Philadelphia, Walker on Thursday said he hasn't visited Buffalo yet and will not report until a new deal is completed. Walker has two years left on his existing contract, but was attempting to negotiate a new deal with the Eagles. Walker's agent, Albert Irby, said the Bills were aware of his client's contract status when they made the trade.