Databinding problem

[Raphael]

Hello everybody,
First of all sorry for my english....
I have a problem with databing and dataset update
example situation....

my form contains:

Textbox1
Textbox2
Combobox1

my Dataset contains 3 table:
Author ----< Book ----< Publisher
----< Relationship)

On my form I begin the binding in the following way:

Me.Textbox1.DataBindings.Add("Text", ds, "Author.Name")
Me.Textbox2.DataBindings.Add("Text", ds, "Publisher.pubName")

Me.Combobox1.DataSource = ds.Tables("Book")
Me.Combobox1.DisplayMember = "Title"
Me.Combobox1.ValueMember = "Title"
Me.Combobox1.DataBindings.Add("SelectedValue", ds, "Author.Title")

Ok now I add a new author, I fill my form end at the end I call the update function.

sdaAutore.Update(dataset.Tables!Author)

And here begins my problem!

The author table as the following fields:
AuthorID
Name
pubName
Title

Where AuthorID field as identity;
Name field is bound to textbox1;
Title field is bound to combobox1;

The question is how can I save the PubName value in my dataset?

Thanx Raphael