Clear entry text from ViewModel using RelayCommand - xamarin.forms

Question

I would like to clear entry text from my ViewModel which is binded there. In the code below I tried it by using a RelayCommand, but it doesn't work.
What i want to accomplish: When clicking button named AddQuestionToQuiz, a function is executed by using Command on the button. The function OnCreateQuizClick(), located in my ViewModel, is triggerd and this function needs to clear my entry text, which i don't get for the moment.
I also tried to use a regular Command instead of using a RelayCommand, but also here it doesn't want to work.
EDIT: UNDERNEATH CODE WORKS FINE - GOT UPDATED
Code is used to clear entry text when clicking on a button from your ViewModel, implementing INotifyPropertyChanged Interface
.xaml - code
<Button x:Name="AddQuestionToQuiz" WidthRequest="200" Command="{Binding CreateQuizCommand}" Style="{StaticResource ButtonStyle}" Text="Add question to quiz"></Button>
ViewModel - code
internal class CreateQuizPageViewModel : INotifyPropertyChanged
{
// Quiz Name Input
public String QuizNameInput { get; set; }
private String quizQuestionInput = "";
public String QuizQuestionInput
{
get { return quizQuestionInput; }
set { quizQuestionInput = value; OnPropertyChanged(); }
}
public RelayCommand CreateQuizCommand { get; set; }
public CreateQuizPageViewModel()
{
CreateQuizCommand = new RelayCommand(OnCreateQuizClick);
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public void OnCreateQuizClick()
{
QuizQuestionInput = "";
}
}

Answer 1

EDIT: VIEWMODEL UPDATED
.xaml - code
<Button x:Name="AddQuestionToQuiz" WidthRequest="200" Command="{Binding CreateQuizCommand}" Style="{StaticResource ButtonStyle}" Text="Add question to quiz"></Button>
ViewModel - code
internal class CreateQuizPageViewModel : INotifyPropertyChanged
{
// Quiz Name Input
public String QuizNameInput { get; set; }
private String quizQuestionInput = "";
public String QuizQuestionInput
{
get { return quizQuestionInput; }
set { quizQuestionInput = value; OnPropertyChanged(); }
}
public RelayCommand CreateQuizCommand { get; set; }
public CreateQuizPageViewModel()
{
CreateQuizCommand = new RelayCommand(OnCreateQuizClick);
}
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
public void OnCreateQuizClick()
{
QuizQuestionInput = "";
}
}