diff --git a/line.py b/line.py
index 0c3401a..97de80b 100644
--- a/line.py
+++ b/line.py
@@ -815,10 +815,10 @@ class Line(SecondCurrencyMixin, Workflow, ModelSQL, ModelView):
         """ compute debit/credit from amount
         """
         if isinstance(values, dict):
-            type_ = values.get('bookingtype', None)
+            type_ = values.get('bookingtype', getattr(line, 'bookingtype', None))
             amount = values.get('amount', None)
         else :
-            type_ = getattr(values, 'bookingtype', None)
+            type_ = getattr(values, 'bookingtype', getattr(line, 'bookingtype', None))
             amount = getattr(values, 'amount', None)
 
         result = {}
@@ -1040,12 +1040,20 @@ class Line(SecondCurrencyMixin, Workflow, ModelSQL, ModelView):
                     values2 = {}
                     values2.update(values)
                     values2.update(cls.clear_by_bookingtype(values, line))
+
+                    # select required fields in case on 'bookingtype'
+                    updt_fields = []
+                    updt_fields.extend(values.keys())
+                    if 'bookingtype' in values.keys():
+                        updt_fields.extend([x for x in fields_update if x not in values.keys()])
+
                     values2.update(cls.get_debit_credit({
-                            x:values.get(x, getattr(line, x)) for x in fields_update
+                            x:values.get(x, getattr(line, x)) for x in updt_fields
                         }, line=line))
                     to_write.extend([lines, values2])
             else :
                 to_write.extend([lines, values])
+
         super(Line, cls).write(*to_write)
 
     @classmethod