Where's the problem?

Quote:

John took out a 2,000,000 construction loan, disbursed to him in three installments. The first installment of 1,000,000 immediately and is followed by two 500,000 installments at 6-month intervals. The interest on the loan is at a rate of 15% convertible semiannually and accumulated to the end of the second year. At that time, the loan and the accumulated interest will be replaced by a 30-year mortgage at 12% convertible monthly. The amount in of the monthly mortgage payment for the first five years will be one-half of the payment for the 6th and later years. The first monthly mortgage payment is due exactly two years after the initial disbursement of the construction loan. Calculate the amount of the 12th mortgage payment.

For the loan, I have 1,000,000(1.075)^4 + 500,000(1.075)^3 + 500,000(1.075)^2 = 2,534,430.079



For the PV of the mortgage, I have .5Xa(Weird double-dot thing of 60 months at 1%) + Xa(Same thing except 300 months at 1%)v^60.



I set the PV of mortgage and AV of loan equal and solved for X to get 33,574.87.

Since this is paid in months, the 12th payment is before the 6th year, so I divided that number by 2 to get 16,787.44.



16,787.44(1.01)^12 = 18,916.51.



:-?

Where's the problem?