Have you replicated the same table structure?
with the invoices being printed from a layout based on LineItems?
If so, then make sure that you find all the lineItems records for your invoice and then print with the Records being browsed option selected.
I just realized that the invoice was printing both products, but it was generating two invoices. Both had the header (address info, table headings, etc) and the trailing grand summary (Subtotal, etc), but the body section (containing the product number, name, etc) was different. Basically it is generating two different invoices - one for each product.
I noticed that you had replied to someone with Printing Invoice wtih Multiple Lines on 10/12/10. It doesn't seem like there was any conclusion posted to that user's problem, so I've put my answers to your questions from that post below, in case you have any ideas as to why this is happening.
Are you using the Invoices starter solution that comes with FileMaker? If so, what version of FileMaker? - Filemaker Pro Advanced v11.0v2
Is this an invoice system with an Invoices table and a portal to a related line items table? - Yes. The invoices table is set up mimicking the SS.
Is your layout based on the Invoices table or the Line Items table? Layout is based on the Line Items table.
If you enter layout mode and double click the "body" part label, do you see any options set for this part that would specify a page break before or after every occurrence? - None of the options are selected.
Hopefully this is helpful. I really appreciate any assistance!
Make sure that you layout is divided correctly into header, body and trailing grand summary layout parts. I think you do, but let's make sure.
The layout uses a very narrow body. It's very easy to get the fields inside the body a pixel too high so that they touch the boundary between the header and the body. Try Selecting all the fields in your body while in layout mode and press the down arrow to nudge them all down one pixel. Then preview the layout and see if it now previews correctly.
PS. FileMaker Pro's latest version is 11.0v3 and you can down load a free updater--which applies a small number of "bug fixes" from the downloads link at the top of this screen.
Moving the fields just a bit lower seemed to fix the problem. Thanks for your help!