Wash Sale on 1099-B

I have a question relating to entering a 1099-B into Turbo-tax that includes a wash sale. The transaction is 

Proceeds = $13500

Cost Basis = $13000

Box 1 G = Code W (Wash Sale Disallowed) $250

 

After I entered all the data, the summary line for this entry shows the wash sale ($250) under the Adjustment column and it shows a total Gain of $750. From what I understand of the tax rules, the amount of the wash sale should be added to the cost basis of the shares that remain in the account after the sale. When I eventually sell those shares, I would get the benefit of the loss in the form of a higher cost basis. Therefore I would expect Turbotax to show a gain of $500 on this transaction, not $750. Why does TurboTax add the wash sale amount to the total gain? Thanks in advance for your responses.