For the month of February 2018, the value of sales returns received is more than the sales during the month.
Generally, in GSTR-3B, we reduce the amount of sales return from the sales and while filing GSTR-1 we give the breakup of Sale invoices and credit notes.
But now, since "Sales - Sales Returns" is a negative figure, GSTR-3B is not taking the negative amount in the field.