Mortgage amortization not working

[Donald Allen]

I am running Gnucash 2.2.9 on an up-to-date Arch Linux system. The
payment of my home mortgage is entered into Gnucash by a scheduled
transaction. The problem is that the scheduled transaction does not do
the mortgage amortization correctly, though that is what I intended
when I set it up and it did work for awhile.

I refinanced my mortgage on 5/1/2004, a 10-year fixed-rate mortage at 4.625%.

The Overview tab of the scheduled transaction shows the Enabled and
Create automatically boxes checked. In the Occurrences section, the
Until radio button is selected, with the date set to 5/1/2014.

The Frequency tab has the frequency set to Monthly, start date =
5/1/2004, every = 1 months, on the 1st.

The template transaction looks like this (I’ve substituted x for the
original amount of the mortgage for privacy reasons):

Description								Tot debit	Tot credit
Mortgage payment - Payment	Assets:Checking		n			pmt( 0.04625 / 12 :
120.00 : x : 0 : 0 )
Mortgage payment - Principal	Liabilities:Mortgage		n	ppmt( 0.04625 /
12 : i : 120.00 : x : 0 : 0 )
Mortgage payment - Interest	Expenses:House:Mortgage int.	n	ipmt(
0.04625 / 12 : i : 120.00 : x : 0 : 0 )

(Apologies for the alignment, if it doesn't look right. Tabs are a
problem in Gmail. The formula for the payment is in the Tot credit
column, those for the Principal and Interest are in the Tot debit
column.)

What is happening is that every month, I get an automatically
generated transaction where the principal and interest payments are
those that would be correct if the payment were dated 3/1/2008. So I’m
getting this constant 3/1/2008 payment every month and every month I
go in and fix it, having calculated the correct amortization
separately.

This would appear to be a bug, though it’s certainly possible I’m
doing something wrong.

Ideas?

/Don Allen