Wpf checkbox binding not working in MVVM model.

<ListView Grid.Row="1" Name="listbox" ItemsSource="{Binding Items}"   Margin="5,5,5,5" Width="Auto" >

                <ListView.View >
                    <GridView  >

                        <GridViewColumn Width="80"  >
                        <GridViewColumn.Header >
                            <CheckBox  x:Name="cbSelectAll" IsChecked="{Binding ModelDetails.IsChecked}"  Command="{Binding cbSelectAll_Checked}"/>
                        </GridViewColumn.Header>

                            <GridViewColumn.CellTemplate>
                                <DataTemplate>
                                    <StackPanel Orientation="Horizontal">
                                    <WrapPanel x:Name="Layout"   >
                                       <CheckBox  IsChecked="{Binding IsSelected, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
                                    </WrapPanel>
                                </StackPanel>
                                </DataTemplate>
                            </GridViewColumn.CellTemplate>
                        </GridViewColumn>
                      </ListView.View >
                    </GridView  >  
                  </ListView>

class ViTypeModel : INotifyPropertyChanged
    {
        private bool _isSelected;
        private bool _isChecked;
        //Define an event based on delegates
        public event PropertyChangedEventHandler PropertyChanged;
        //Raise the event
        public void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                //publishing the event in current classs
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
public bool IsChecked
        {
            get
            {
                return _isChecked;
            }
            set
            {
                _isChecked = value;
                OnPropertyChanged(nameof(IsChecked));
            }
        }

        public bool IsSelected
        {
            get
            {
                return _isSelected;
            }
            set
            {
                _isSelected = value;
                OnPropertyChanged(nameof(IsSelected));
            }
        }

private ViTypeModel _ModelDetails;


        public ViTypeModel ModelDetails
        {
            get
            {
                return _ModelDetails;
            }
            set
            {
                _ModelDetails = value;
            }
        }

public void SelectAllBtnExecute(object param)
      {

          foreach (var selectedItems in Items)
          {
              ModelDetails.IsSelected = ModelDetails.IsChecked;
          }

      }