My mortgage credit certificate is only partially applied, w/ a carryover credit of $758. I owe more than that, why isn't my full credit applying to this year?

My total MCC credit is $1,746, Turbotax is only utilizing $988 of the credit and giving me a carryover of $758.  However, I owe greater than $758 of taxes, so don't understand why my credit isn't being fully applied for this tax year.