How did you enter the sale? Using the "Stocks, Mutual Funds, Bonds, Other" interview and telling TurboTax that you didn't receive a 1099-B? And then selecting "Land" as what was sold? That would place the $12,000 loss on Form 8949, and that loss, along with any others for that particular "sales category" would transfer to Schedule D to be netted against other gains. Only if you still had a loss would you get the loss - on line 13 of your Form 1040, not down in the "tax credits" area - up to the $3,000 limit.
Follow the number flow.
