Pre-Payroll - DBA amount on Pay Stub is different than DBA application

This week on our Pre-Payroll for December, an employee's medical deduction line item showed $30.78 on the Pay Stub but the total deduction on the pay stub was summarized with the $31.25 amount (which is the correct amount). Also, the DBA screen also showed the $31.25 amount.

We received a Gross-To-Net error that is why we had discovered this issue (the employee's paystub total deductions don’t match the sum of the deductions showing on the paystub).

The payroll was back dated to include adjustments for October and November time. 

Should this be the issue because we also seem to have issues when we back date our payroll?