If the parental record contains the required information for payment to be processed but it is listed as paytype not active, it is likely to be caused by there being no whole weeks to pay in the period.
If there is less than a week between the payment start date and the pay date or earnings period date, the record will be unable to pay.
If you wish for the record to pay part weeks, you will need to enable align to pay date within the parental record.