C# if else is not executing

the if else statements doesnt executes...here is the code: this should compute the discount and the total amount of item purchsed depending on the date it was paid DateTime dPurchase, dPaid; int amount; double discount, totalAmount, days;

        S.Write("Purchase amount: ");
        amount = Convert.ToInt16(S.ReadLine());
        S.Write("Date Purchased: ");
        dPurchase = Convert.ToDateTime(S.ReadLine());
        S.Write("Date to be Paid: ");
        dPaid = Convert.ToDateTime(S.ReadLine());

        days = dPaid.Subtract(dPurchase).TotalDays;

        if (days <= 10) {
            discount = amount * 0.2;
            totalAmount = amount - discount;
            S.Write("Discount: " + discount + "\nTotal Amount: " + totalAmount);
        }
        else if (days <= 25){
            discount = amount * 0.15;
            totalAmount = amount - discount;
            S.Write("Discount: " + discount + "\nTotal Amount: " + totalAmount);
        }
        else if (days <= 35)
        {
            discount = amount * 0.1;
            totalAmount = amount - discount;
            S.Write("Discount: " + discount + "\nTotal Amount: " + totalAmount);
        }
        else if (days <= 45)
        {
            discount = amount * 0.05;
            totalAmount = amount - discount;
            S.Write("Discount: " + discount + "\nTotal Amount: " + totalAmount);
        }
        else {
            discount = 0;
            totalAmount = amount;
        }
        S.Write("Days: " + days + "\n");
        S.Write("First Term: " + dPurchase.Date.AddDays(1) + " to " + dPurchase.Date.AddDays(10) + "\n");
        S.Write("Second Term: " + dPurchase.Date.AddDays(11) + " to " + dPurchase.Date.AddDays(25) + "\n");
        S.Write("Third Term: " + dPurchase.Date.AddDays(26) + " to " + dPurchase.Date.AddDays(35) + "\n");
        S.Write("Fourth Term: " + dPurchase.Date.AddDays(36) + " to " + dPurchase.Date.AddDays(45) + "\n");
        S.Write("Fifth Term: " + dPurchase.Date.AddDays(46) + " to " + dPurchase.Date.AddDays(60) + "\n");
        S.ReadKey();

lines after the if..else statements are executing