Report difference Calculation

Need Help, Where am I going wrong? What to find the difference between Payments(First Bold) and Zero rated(Second Bold)

[Ticket Payments:2, 1]
{REPORT PAYMENT DETAILS:P.Name,P.Amount.Sum:((PT=Cash)||(PT=Voucher)) AND (Payment.Amount > 0)}
VAT @16%|{REPORT TICKET DETAILS:T.Tax.sum}
Zero Rated Total |{REPORT ORDER DETAILS:O.Total.sum:(MG=Bread)}
Taxable Amount|[{REPORT ORDER DETAILS:O.Total.sum:(MG=Bread)}-{REPORT PAYMENT TOTAL:(PT=Cash)||(PT=Credit Card)}]