Lookup last payment received date
I am using FM Pro 8.5v1 on OSX 10.5.8. The FM database I'm using was created by someone else and I have fairly limited knowledge/experience with databases. What I've been able to do so far has been pretty much done through trial and error, with some luck thrown in. The issue I've come across is I'm trying to create a field that will lookup when we last received a payment from a customer. Right now I have all the fields to make up a statement/invoice and a "paid date" for each one of those invoices. So say ABC Inc. has been billed four time in the past and all of them have been paid with paid dates of 7/20/09, 8/5/09, 8/16/09, and 9/27/09. On the next invoice I create for them I want to be able to show that the last payment received was on 9/27/09. Any help would be greatly appreciated. If more info is needed, please let me know. Thanks.