Home mortgage interest worksheets dont add up to my schedule A entry

Line 8a of my schedule A is 13,396.  The interest from my three 1098s (1st home, 2nd home, and HELOC). add up to  19121.15.  The HELOC is less than $100,000 and the total of the three loans is less than $750,000.  Where does the $13,396 come from?