diff --git a/modules/purchase_trade/invoice.py b/modules/purchase_trade/invoice.py
index dc9ed6f..6c7a4b5 100644
--- a/modules/purchase_trade/invoice.py
+++ b/modules/purchase_trade/invoice.py
@@ -1,6 +1,7 @@
 from decimal import Decimal, ROUND_HALF_UP
 from datetime import date as dt_date
 import os
+import logging
 from pathlib import Path
 
 from sql import Literal
@@ -19,6 +20,8 @@ from trytond.modules.sale.sale import SaleReport as BaseSaleReport
 from trytond.modules.purchase.purchase import (
     PurchaseReport as BasePurchaseReport)
 
+logger = logging.getLogger(__name__)
+
 
 class InvoiceLineLotWeight(ModelSQL, ModelView):
     "Invoice Line Lot Weight"
@@ -926,6 +929,20 @@ class Invoice(metaclass=PoolMeta):
     def _get_report_weight_adjustment_totals(self):
         reused_lots = self._get_report_reused_lot_lines()
         if not reused_lots:
+            logger.warning(
+                "REPORT_WEIGHT_ADJUSTMENT_NO_REUSED_LOTS: invoice=%s "
+                "line_count=%s lines=%s",
+                getattr(self, 'id', None),
+                len(self._get_report_invoice_lines()),
+                [
+                    {
+                        'line': getattr(line, 'id', None),
+                        'quantity': str(getattr(line, 'quantity', None)),
+                        'lot': getattr(getattr(line, 'lot', None), 'id', None),
+                        'lot_keys': self._get_report_line_lot_keys(line),
+                    }
+                    for line in self._get_report_invoice_lines()
+                ])
             return None
 
         invoice_total = Decimal(0)
@@ -934,6 +951,12 @@ class Invoice(metaclass=PoolMeta):
         for data in reused_lots.values():
             lot = data['lot']
             lines = data['lines']
+            logger.warning(
+                "REPORT_WEIGHT_ADJUSTMENT_GROUP: invoice=%s lot=%s "
+                "line_ids=%s quantities=%s",
+                getattr(self, 'id', None), getattr(lot, 'id', None),
+                [getattr(line, 'id', None) for line in lines],
+                [str(getattr(line, 'quantity', None)) for line in lines])
             negative_lines = [
                 line for line in lines
                 if Decimal(str(getattr(line, 'quantity', 0) or 0)) < 0
@@ -943,18 +966,47 @@ class Invoice(metaclass=PoolMeta):
                 if Decimal(str(getattr(line, 'quantity', 0) or 0)) > 0
             ]
             if not negative_lines or not positive_lines:
+                logger.warning(
+                    "REPORT_WEIGHT_ADJUSTMENT_SKIP_GROUP: invoice=%s lot=%s "
+                    "negative=%s positive=%s",
+                    getattr(self, 'id', None), getattr(lot, 'id', None),
+                    [str(getattr(line, 'quantity', None))
+                        for line in negative_lines],
+                    [str(getattr(line, 'quantity', None))
+                        for line in positive_lines])
                 continue
 
-            invoice_total += sum(
+            invoice_values = [
                 abs(self._get_report_invoice_line_weights(line)[0])
-                for line in negative_lines)
-            landed_total += sum(
+                for line in negative_lines]
+            landed_values = [
                 abs(self._get_report_invoice_line_quantity_from_line(line))
-                for line in positive_lines)
+                for line in positive_lines]
+            logger.warning(
+                "REPORT_WEIGHT_ADJUSTMENT_VALUES: invoice=%s lot=%s "
+                "negative_raw=%s invoice_values=%s positive_raw=%s "
+                "landed_values=%s",
+                getattr(self, 'id', None), getattr(lot, 'id', None),
+                [str(getattr(line, 'quantity', None))
+                    for line in negative_lines],
+                [str(value) for value in invoice_values],
+                [str(getattr(line, 'quantity', None))
+                    for line in positive_lines],
+                [str(value) for value in landed_values])
+            invoice_total += sum(invoice_values)
+            landed_total += sum(landed_values)
             matched = True
 
         if not matched:
+            logger.warning(
+                "REPORT_WEIGHT_ADJUSTMENT_NO_MATCH: invoice=%s reused_lots=%s",
+                getattr(self, 'id', None), list(reused_lots.keys()))
             return None
+        logger.warning(
+            "REPORT_WEIGHT_ADJUSTMENT_RESULT: invoice=%s invoice_weight=%s "
+            "landed_weight=%s difference=%s",
+            getattr(self, 'id', None), invoice_total, landed_total,
+            abs(landed_total - invoice_total))
         return {
             'invoice': invoice_total,
             'landed': landed_total,
@@ -1776,6 +1828,9 @@ class Invoice(metaclass=PoolMeta):
         if self.lines:
             adjustment = self._get_report_weight_adjustment_totals()
             if adjustment:
+                logger.warning(
+                    "REPORT_WEIGHT_ADJUSTMENT_USE_GROSS: invoice=%s value=%s",
+                    getattr(self, 'id', None), adjustment['landed'])
                 return adjustment['landed']
             reused_gross = self._get_report_reused_lot_gross_total()
             if reused_gross is not None:
@@ -1800,6 +1855,9 @@ class Invoice(metaclass=PoolMeta):
         if self.lines:
             adjustment = self._get_report_weight_adjustment_totals()
             if adjustment:
+                logger.warning(
+                    "REPORT_WEIGHT_ADJUSTMENT_USE_NET: invoice=%s value=%s",
+                    getattr(self, 'id', None), adjustment['invoice'])
                 return adjustment['invoice']
             return sum(
                 self._get_report_invoice_line_weights(line)[0]
@@ -1836,6 +1894,10 @@ class Invoice(metaclass=PoolMeta):
     def report_weight_difference(self):
         adjustment = self._get_report_weight_adjustment_totals()
         if adjustment:
+            logger.warning(
+                "REPORT_WEIGHT_ADJUSTMENT_USE_DIFFERENCE: invoice=%s "
+                "value=%s",
+                getattr(self, 'id', None), adjustment['difference'])
             return adjustment['difference']
         gross = self.report_gross
         net = self.report_net