RaisePropertyChanged doesn't work for ObservableCollection - mvvm

Question

I have a really weird problem with update UI using MVVM Light Toolkit. The RaisePropertyChanged doesn't work at all for my ObservableCollection.
Here is the XAML code:
<ListBox x:Name="list" ItemsSource="{Binding ModelList}" SelectedItem="{Binding SelectedItem, Mode=TwoWay}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Name}"></TextBlock>
<CheckBox IsChecked="{Binding IsChecked}"></CheckBox>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
<interaction:Interaction.Triggers>
<interaction:EventTrigger EventName="SelectionChanged">
<cmd:EventToCommand Command="{Binding TempCommand}" CommandParameter="{Binding ElementName=list, Path=SelectedItem}"
PassEventArgsToCommand="True"/>
</interaction:EventTrigger>
</interaction:Interaction.Triggers>
</ListBox>
And there is ViewModel code part:
private Model _selectedItem;
public Model SelectedItem
{
get { return _selectedItem; }
set
{
_selectedItem = value;
RaisePropertyChanged("SelectedItem");
}
}
private ObservableCollection<Model> _modelList;
public ObservableCollection<Model> ModelList
{
get { return _modelList; }
set
{
_modelList = value;
RaisePropertyChanged("ModelList");
}
}
public RelayCommand<Model> TempCommand { get; private set; }
/// <summary>
/// Initializes a new instance of the MainViewModel class.
/// </summary>
public MainViewModel()
{
modelList = new ObservableCollection<Model>()
{
new Model()
{
IsChecked = true,
Name = "Temp1"
},
new Model()
{
IsChecked = false,
Name = "Temp2"
},
new Model()
{
IsChecked = false,
Name = "Temp3"
}
};
ModelList = modelList;
TempCommand = new RelayCommand<Model>(Model_SelectedItem);
}
private void Model_SelectedItem(Model item)
{
// What should I do here?
}
When I change the ModelList - there is no reaction from ListBox UI.
Anyone can help me ?

Answer 1

Problem solved.
When you have custom class in ObservableCollection or List it has to derived from ObservableObject and all the Properties have to fire RaisePropertyChanged event.