diff --git a/book.py b/book.py
index fde854d..a3704ed 100644
--- a/book.py
+++ b/book.py
@@ -28,6 +28,9 @@ STATES2 = {
         ),
     'invisible': ~Bool(Eval('btype')),
     }
+STATES3 = {}
+STATES3.update(STATES2)
+STATES3['required'] = ~STATES2['invisible']
 DEPENDS2 = ['state', 'btype']
 
 sel_state_book = [
@@ -83,10 +86,7 @@ class Book(tree(separator='/'), Workflow, ModelSQL, ModelView):
                 ('company', '=', Eval('company', -1)),
                 ],
             ],
-        states={
-            'readonly': STATES2['readonly'],
-            'required': Bool(Eval('btype')),
-        }, depends=DEPENDS2+['company'])
+        states=STATES3, depends=DEPENDS2+['company'])
     number_atcheck = fields.Boolean(string="number when 'Checking'",
         help="The numbering of the lines is done in the step Check. If the check mark is inactive, this happens with Done.",
         states=STATES2, depends=DEPENDS2)
@@ -97,7 +97,7 @@ class Book(tree(separator='/'), Workflow, ModelSQL, ModelView):
                 Bool(Eval('lines')),
                 ),
             'invisible': STATES2['invisible'],
-            'required': Bool(Eval('btype')),
+            'required': ~STATES2['invisible'],
         }, depends=DEPENDS2+['lines'])
     balance = fields.Function(fields.Numeric(string='Balance', readonly=True,
         digits=(16, Eval('currency_digits', 2)),
@@ -110,7 +110,7 @@ class Book(tree(separator='/'), Workflow, ModelSQL, ModelView):
                 Bool(Eval('lines', [])),
                 ),
             'invisible': STATES2['invisible'],
-            'required': Bool(Eval('btype')),
+            'required': ~STATES2['invisible'],
         }, depends=DEPENDS2+['lines'])
     currency_digits = fields.Function(fields.Integer(string='Currency Digits',
         readonly=True), 'on_change_with_currency_digits')