Hello, I have Odoo 8.

I want to display a report like this:

Row: partner name

And for each partner name, display the balance and the date of the last payment.

This is my XML file:

<graph string="Lista de deudores" type="pivot">
       <field name="last_payment_date" type="measure" />
       <field name="balance" type="measure"/>
       <field name="partner" type="row"/>                 
</graph>

But the "last payment" col is empty. Why? If I try the PostgreSQL query it works OK, there is not the problem