Cupertino Date Picker Flutter NoSuchMethod error (datePickerHour()) in implementation

Question

Im new in Flutter and Im having troubles implementing a Date Picker Widget, that I have already tested apart, in my App. It just throws an error NoSuchMethodError-> The method 'datePickerHour' was called on null. Receiver: null Tried calling: datePickerHour(0)

Ive included the right cupertino package and Ive done the implementation exactly as in my previous testing code. I just dont get why is this method (datePickerHour()) inside CupertinoDatePicker not being recognized. Could somebody help me spotting the error? Thank you in advance.

Code is:

                                  FlatButton(
                                      onPressed: () {                                             
                                          showModalBottomSheet(
                                              context: context,
                                              builder:
                                                  (BuildContext builder) {
                                                return Container(
                                                  height:
                                                      MediaQuery.of(context)
                                                              .copyWith()
                                                              .size
                                                              .height /
                                                          3,
                                                  color: Colors.white,
                                                  child:
                                                      CupertinoDatePicker(
                                                    mode:
                                                        CupertinoDatePickerMode
                                                            .dateAndTime,
                                                    onDateTimeChanged:
                                                        (picked) {
                                                      if (picked != null &&
                                                          picked !=
                                                              selectedDate)
                                                        setState(() {
                                                          selectedDate =
                                                              picked;
                                                        });
                                                    },
                                         
                                                    initialDateTime: selectedDate,
                                                    minimumYear: 2020,
                                                    maximumYear: 2025,
                                                  ),
                                                );
                                              });
                                        }
                                      },
                                      padding: EdgeInsets.symmetric(
                                          vertical: 14),
                                      color: Theme.of(context).accentColor,
                                      shape: StadiumBorder(),
                                      child: Icon(
                                        Icons.calendar_today,
                                        color:
                                            Theme.of(context).primaryColor,
                                      )),
                                  

Answer 1

add this

MaterialApp(
  localizationsDelegates: [
    GlobalMaterialLocalizations.delegate,
    GlobalWidgetsLocalizations.delegate
  ],
  supportedLocales: [
    const Locale('ru', "RU"),
    const Locale('en', "US"),
  ],