=== modified file 'account/report/account_invoice_report.py'
--- account/report/account_invoice_report.py	2011-01-25 14:18:33 +0000
+++ account/report/account_invoice_report.py	2011-04-02 10:46:18 +0000
@@ -107,18 +107,25 @@
                     ai.address_invoice_id as address_invoice_id,
                     ai.account_id as account_id,
                     ai.partner_bank_id as partner_bank_id,
+-- FIXED avoid multiply -1 and use -<field> 
                     sum(case when ai.type in ('out_refund','in_invoice') then
-                         ail.quantity / u.factor * -1
+                         -ail.quantity / u.factor 
                         else
                          ail.quantity / u.factor
                         end) as product_qty,
+
+-- FIXED using price_subtotal respects discounts, which is relevant for net
                     sum(case when ai.type in ('out_refund','in_invoice') then
-                         ail.quantity*ail.price_unit * -1
+                         -ail.price_subtotal 
                         else
-                         ail.quantity*ail.price_unit
+                          ail.price_subtotal
                         end) / cr.rate as price_total,
+
+--
+-- FIXME the line total incl tax can't be caculated by deviding the invoice total / number of lines
+-- 
                     sum(case when ai.type in ('out_refund','in_invoice') then
-                         ai.amount_total * -1
+                         -ai.amount_total
                         else
                          ai.amount_total
                          end) / (CASE WHEN 
@@ -131,17 +138,15 @@
                                where a.id=ai.id) 
                             ELSE 1 
                             END) / cr.rate as price_total_tax,
+
                     (case when ai.type in ('out_refund','in_invoice') then
-                      sum(ail.quantity*ail.price_unit*-1)
+                      sum(-ail.price_subtotal)
                     else
-                      sum(ail.quantity*ail.price_unit)
-                    end) / (CASE WHEN
-                         (case when ai.type in ('out_refund','in_invoice') 
-                          then sum(ail.quantity/u.factor*-1)
-                          else sum(ail.quantity/u.factor) end) <> 0 
+                      sum(ail.price_subtotal)
+                    end) / (CASE WHEN sum(ail.quantity/u.factor) <> 0 
                        THEN 
                          (case when ai.type in ('out_refund','in_invoice') 
-                          then sum(ail.quantity/u.factor*-1)
+                          then sum(-ail.quantity/u.factor)
                           else sum(ail.quantity/u.factor) end) 
                        ELSE 1 
                        END)
@@ -159,7 +164,7 @@
                         left join account_invoice_line as l ON (a.id=l.invoice_id)
                         where a.id=ai.id)) as due_delay,
                     (case when ai.type in ('out_refund','in_invoice') then
-                      ai.residual * -1
+                      -ai.residual
                     else
                       ai.residual
                     end)/ (CASE WHEN 
@@ -174,7 +179,9 @@
                        END) / cr.rate as residual
                 from account_invoice_line as ail
                 left join account_invoice as ai ON (ai.id=ail.invoice_id)
-                left join product_template pt on (pt.id=ail.product_id)
+-- FIXED wrong join 		
+                left join product_product pr on (pr.id=ail.product_id)
+                left join product_template pt on (pt.id=pr.product_tmpl_id)
                 left join product_uom u on (u.id=ail.uos_id),
                 res_currency_rate cr
                 where cr.id in (select id from res_currency_rate cr2  where (cr2.currency_id = ai.currency_id)