Nested tables fall apart after an email

I have nested tables that work fine.    Here's how they look:

As an fyi - the code behind is:

• Add buttons - $.parent.tbl.Row.instanceManager.addInstance();
• Remove buttons - $.parent.instanceManager.removeInstance($.parent.index);
• email

var cDoc = event.target;

var aUrl="mailto:peter.gaston@gmail.com?subject=test&body=testtesttest";

cDoc.submitForm({ cURL: aUrl, cSubmitAs: "PDF", cCharSet: "utf-8" });

And, after the email, the attachment looks like this, i.e., the nested tables have fallen apart. 

Ideas?    Explanations?   ???