Making payments against an invoice

[Iain Mac Donald <..hidden..>]

The answer to this question is probably blindingly obvious but I have
struggled with it for several hours now.

I am using test data in LS 1.2.5 and I have not altered the account
structure after the initial install. 

I simulate a customer payment against an invoice using the Payments
fields at the bottom of the screen. I then select "Update" and the
screen refreshes showing the payment. But this data does not get saved
anywhere. When I come back to this invoice the data entered is
missing.

What should I do to submit a payment against this invoice?


-- 
Kind regards,
Iain.