UWP DataGrid wont update the UI when the Item Source was changed in c# - mvvm

Question

Hi on my UWP app i use a DataGrid control (microsoft community nuget) it updates on load but when added new items it wont get update the UI. when at start the app trigger and load from the data source but after added new items it wont get refreshed even tho the ObservableCollection get changed. data add through a ContentDialog, does ContentDialog block call to the frame when get called ?
<controls:DataGrid x:Name="DataGrid1" ItemsSource="{x:Bind ViewModel.Collection,Mode=OneWay}" Foreground="White"
Grid.Row="1"
Margin="12"
VerticalAlignment="Stretch"
HorizontalAlignment="Stretch"
HorizontalScrollBarVisibility="Visible"
VerticalScrollBarVisibility="Visible"
AlternatingRowBackground="Transparent"
AlternatingRowForeground="Gray"
AreRowDetailsFrozen="False"
AutoGenerateColumns="False"
CanUserSortColumns="False"
CanUserResizeColumns="False"
CanUserReorderColumns="True"
ColumnHeaderHeight="32"
MaxColumnWidth="400"
IsReadOnly="False"
RowDetailsVisibilityMode="VisibleWhenSelected"
SelectionMode="Extended">
<controls:DataGrid.Columns>
<controls:DataGridTextColumn
x:Name="id"
Header="ID"
Width="SizeToHeader"
Binding="{Binding ID,Mode=OneWay}"
FontSize="20"
Visibility="Visible">
<controls:DataGridTextColumn.ElementStyle>
<Style TargetType="TextBlock">
<Setter Property="TextWrapping" Value="Wrap"/>
</Style>
</controls:DataGridTextColumn.ElementStyle>
</controls:DataGridTextColumn>
<controls:DataGridTextColumn
Header="ID"
Width="SizeToHeader"
Binding="{Binding Number,Mode=OneWay}"
Tag="ID"
FontSize="20" />
<controls:DataGridTextColumn
Header="ID"
Width="SizeToHeader"
Binding="{Binding Name,Mode=OneWay}"
FontSize="20" />
<controls:DataGridTextColumn
Header="ID"
Width="SizeToHeader"
Binding="{Binding StartDate,Mode=OneWay}"
FontSize="20" />
<controls:DataGridTextColumn
Header="ID"
Width="SizeToHeader"
Binding="{Binding EndDate,Mode=OneWay}"
FontSize="20" />
</controls:DataGrid.Columns>
</controls:DataGrid>
</Grid>
Here is my viewmodel
class PermitsViewModel : INotifyPropertyChanged
{
//public List<PermitData> PermitsData { get; set; }
public ObservableCollection<PermitData> Collection
{
get
{
return Collection;
}
set
{
Collection = value;
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs("Collection"));
}
}
}
private static Frame _EntryFrame;
public PermitsViewModel() {
//PermitsData = new List<PermitData> {
//new PermitData { ID = 9966615, Number = 78, Name = "Mark", StartDate = new DateTime(2016, 8, 30), EndDate = new DateTime(2017, 5, 30) },
//new PermitData { ID = 9945512, Number = 79, Name = "Steve", StartDate = new DateTime(2019, 7, 30), EndDate = new DateTime(2015, 9, 30) }
//};
Collection = new ObservableCollection<PermitData>();
Collection.Add(new PermitData { ID = 22, Number = 22, Name = "KASUN", StartDate = new DateTime(2016, 8, 30), EndDate = new DateTime(2016, 8, 30) });
OnPropertyChanged();
}
public void AddToTable(int ID, int Number, string Name, DateTime StDate, DateTime EndDate)
{
//Collection = new ObservableCollection<PermitData>();
Collection.Add(new PermitData { ID = ID, Number = Number, Name = Name, StartDate = new DateTime(2016, 8, 30), EndDate = new DateTime(2016, 8, 30) });
Debug.WriteLine(Collection[0]);
//OnPropertyChanged();
}
}
Data property layer
class PermitData
{
public int ID { get; set; }
public int Number { get; set; }
public string Name { get; set; }
public DateTime StartDate { get; set; }
public DateTime EndDate { get; set; }
}
main
public sealed partial class Permits : Page
{
PermitsViewModel ViewModel { get; } = new PermitsViewModel();
public Permits()
{
this.InitializeComponent();
ViewModel.Init(DataEntryPort);
base.DataContext = ViewModel;
}
}