Why does Turbo Tax show long term capital gain on a short term transaction

Investment was in a Limited Maturity Bond Fund (Mutual Fund) for less than one year. 1099-B shows a gain which is reported by Turbo Tax on Schedule D, Line 7. But then Turbo Tax shows a long term gain on Lines 13 and 15 and adds Lines 7 and 15 and reports that amount on Line 16.  No where on the 1099-B form does it indicate a long term gain and this investment was less than one year.  Any idea of how Turbo Tax would come up with a long term gain on a short term investment?