diff --git a/planner.py b/planner.py
index 6d46fad..d1dfd6a 100644
--- a/planner.py
+++ b/planner.py
@@ -85,8 +85,6 @@ class ScheduledBooking(DeactivableMixin, ModelSQL, ModelView):
         help='the next 5 appointments based on the configured rule'),
         'on_change_with_nextdates')
 
-    # rrule: frequ, dtstart, until, bymonthday
-
     @classmethod
     def __setup__(cls):
         super(ScheduledBooking, cls).__setup__()
@@ -125,12 +123,11 @@ class ScheduledBooking(DeactivableMixin, ModelSQL, ModelView):
             'year': YEARLY, 'month': MONTHLY, 'week': WEEKLY, 'day': DAILY}
         pweekday = {
             '0': MO, '1': TU, '2': WE, '3': TH, '4': FR, '5': SA, '6': SU,
-            '99': None}
+            '99': None}.get(params.get('weekday', self.weekday), None)
 
-        if (count is None) or (count > 100):
-            count = 100
-        if count < 1:
-            count = 1
+        if count is None:
+            count = 5
+        count = 1 if count < 1 else 100 if count > 100 else count
 
         end_date = params.get('end_date', self.end_date)
         frequ = pfrequ[params.get('frequ', self.frequ)]
@@ -144,11 +141,15 @@ class ScheduledBooking(DeactivableMixin, ModelSQL, ModelView):
             monthday = 1 if monthday < 1 else 31 if monthday > 31 else monthday
 
         interval = params.get('interval', self.interval)
+        if interval is None:
+            interval = 1
         interval = 1 if interval < 1 else 10 if interval > 10 else interval
 
+        assert (monthday is None) or (pweekday is None), \
+            "weekday and monthday cannot be used together"
+
         dtrule = rrule(
-            freq=frequ,
-            byweekday=pweekday[params.get('weekday', self.weekday)],
+            freq=frequ, byweekday=pweekday,
             dtstart=params.get('start_date', self.start_date),
             until=end_date,
             bysetpos=setpos if frequ == MONTHLY else None,
diff --git a/tests/planner.py b/tests/planner.py
index 0041e69..d23fa40 100644
--- a/tests/planner.py
+++ b/tests/planner.py
@@ -56,7 +56,7 @@ class PlannerTestCase(object):
 
     @with_transaction()
     def test_planner_create_job(self):
-        """ create job, check rule
+        """ create job, check rule + constraints
         """
         Planner = Pool().get('cashbook.planner')
 
@@ -107,7 +107,104 @@ class PlannerTestCase(object):
                 start_date=date(2022, 5, 1),
                 params={
                     'end_date': date(2022, 9, 15), 'weekday': '2',
-                    'interval': 2, 'setpos': 1}),
+                    'interval': 2, 'setpos': 1, 'monthday': None}),
             [date(2022, 5, 4), date(2022, 7, 6), date(2022, 9, 7)])
 
+        # 2nd wednesday of each 2nd month
+        self.assertEqual(
+            job._compute_dates_by_rrule(
+                start_date=date(2022, 5, 1),
+                params={
+                    'end_date': date(2022, 9, 15), 'weekday': '2',
+                    'interval': 2, 'setpos': 2, 'monthday': None}),
+            [date(2022, 5, 11), date(2022, 7, 13), date(2022, 9, 14)])
+
+        # 2nd wednesday of each month, 6x occurences
+        self.assertEqual(
+            job._compute_dates_by_rrule(
+                start_date=date(2022, 5, 1), count=6,
+                params={
+                    'weekday': '2', 'end_date': None,
+                    'interval': 1, 'setpos': 2, 'monthday': None}),
+            [date(2022, 5, 11), date(2022, 6, 8), date(2022, 7, 13),
+                date(2022, 8, 10), date(2022, 9, 14), date(2022, 10, 12)])
+
+        Planner.write(*[[job],  {
+            'frequ': 'year', 'start_date': date(2022, 5, 1),
+            'setpos': None, 'monthday': None, 'interval': 1,
+            'weekday': '99'}])
+
+        # invalid end_date
+        self.assertRaisesRegex(
+            UserError,
+            'The value "2022-04-30" for field "End Date" in "Job 1" of ' +
+            '"Scheduled Booking" is not valid according to its domain.',
+            Planner.write,
+            *[[job],  {
+                'frequ': 'year', 'start_date': date(2022, 5, 1),
+                'end_date': date(2022, 4, 30)}])
+
+        # monthday and weekday used together
+        self.assertRaisesRegex(
+            UserError,
+            'The value "2" for field "Day of month" in "Job 1" of ' +
+            '"Scheduled Booking" is not valid according to its domain.',
+            Planner.write,
+            *[[job],  {
+                'frequ': 'month', 'start_date': date(2022, 5, 1),
+                'monthday': 2, 'weekday': '1', 'end_date': None}])
+
+        # monthday out of range 1
+        self.assertRaisesRegex(
+            UserError,
+            'The value "0" for field "Day of month" in "Job 1" of ' +
+            '"Scheduled Booking" is not valid according to its domain.',
+            Planner.write,
+            *[[job],  {
+                'frequ': 'year', 'start_date': date(2022, 5, 1),
+                'monthday': 0, 'weekday': '99', 'end_date': None}])
+
+        # monthday out of range 2
+        self.assertRaisesRegex(
+            UserError,
+            'The value "32" for field "Day of month" in "Job 1" of ' +
+            '"Scheduled Booking" is not valid according to its domain.',
+            Planner.write,
+            *[[job],  {
+                'frequ': 'year', 'start_date': date(2022, 5, 1),
+                'monthday': 32, 'weekday': '99', 'end_date': None}])
+
+        # invalid usage of setpos
+        self.assertRaisesRegex(
+            UserError,
+            'The value "1" for field "Occurrence" in "Job 1" of ' +
+            '"Scheduled Booking" is not valid according to its domain.',
+            Planner.write,
+            *[[job],  {
+                'frequ': 'year', 'start_date': date(2022, 5, 1),
+                'setpos': 1, 'monthday': None, 'weekday': '99',
+                'end_date': None}])
+
+        # setpos out of range 1
+        self.assertRaisesRegex(
+            UserError,
+            'The value "0" for field "Occurrence" in "Job 1" of ' +
+            '"Scheduled Booking" is not valid according to its domain.',
+            Planner.write,
+            *[[job],  {
+                'frequ': 'month', 'start_date': date(2022, 5, 1),
+                'setpos': 0, 'monthday': None, 'weekday': '2',
+                'end_date': None}])
+
+        # setpos out of range 2
+        self.assertRaisesRegex(
+            UserError,
+            'The value "5" for field "Occurrence" in "Job 1" of ' +
+            '"Scheduled Booking" is not valid according to its domain.',
+            Planner.write,
+            *[[job],  {
+                'frequ': 'month', 'start_date': date(2022, 5, 1),
+                'setpos': 5, 'monthday': None, 'weekday': '2',
+                'end_date': None}])
+
 # end PlannerTestCase