diff --git a/resource_booking/tests/test_backend.py b/resource_booking/tests/test_backend.py
index f91e451e..c264079a 100644
--- a/resource_booking/tests/test_backend.py
+++ b/resource_booking/tests/test_backend.py
@@ -821,7 +821,7 @@ def test_event_show_as_free(self):
         rb_f.start = "2021-03-01 09:30:00"
         rb_f.duration = 0.5
         rb_f.partner_ids.add(self.partner.copy())
-        with self.assertRaises(AssertionError):
+        with self.assertRaises(ValidationError):
             rb_f.save()
 
     def test_resource_is_available(self):
diff --git a/resource_booking/views/resource_booking_views.xml b/resource_booking/views/resource_booking_views.xml
index f017dfca..e27b1c96 100644
--- a/resource_booking/views/resource_booking_views.xml
+++ b/resource_booking/views/resource_booking_views.xml
@@ -153,7 +153,7 @@
                                 <field
                                     name="combination_id"
                                     class="oe_inline"
-                                    attrs="{'required': [('start', '!=', False)], 'readonly': [('combination_auto_assign', '=', True)]}"
+                                    attrs="{'required': [('combination_auto_assign', '=', False)], 'readonly': [('combination_auto_assign', '=', True)]}"
                                 />
                             </div>
                             <field name="categ_ids" widget="many2many_tags" />