You can add more lines only after you have entered data in all the existing blank lines

In creation of Expense Report, warning message “You can add more lines only after you have entered data in all the existing blank lines”. But, there were no blank fields. The mileage can only handle 5 lines per set/records and the issue happened/encountered after deleting the line 6 (for row 6 to 10). Where technically line 6 has been removed and no record/data recorded or no existing blank lines are filled up for line 6 to 10.