The total capital gain on your 1099-DIV is not the same as the gain from you sale of stocks. The gross proceeds on your 1099-B is only the sale price, you need to find out the cost of these stocks. If you can't find it out yourself, you can call the customer service number on the form and ask them to give you the cost basis. The difference between the gross proceeds and the cost basis is your gain or loss. You should report these transactions on schedule D