DataTrigger for Image not responding WPF

Question

I am trying to get my DataTrigger on my image to fire when a boolean is changed in my ViewModel. The code for the image control is:

<Image>
                                    <Image.Style>
                                        <Style TargetType="Image">
                                            <Setter Property="Width" Value="15"/>
                                            <Setter Property="Height" Value="15"/>
                                            <Setter Property="Source" Value="{Binding CloseImage}"/>
                                            <Style.Triggers>
                                                <DataTrigger Binding="{Binding TASI}" Value="True">
                                                    <Setter Property="Source" Value="{Binding CheckImage}"/>
                                                </DataTrigger>
                                            </Style.Triggers>
                                        </Style>
                                    </Image.Style>
                                </Image>

The ViewModel code is:

private bool _TASI;
        public bool TASI
        {
            get { return _TASI; }
            set
            {
                _TASI = value;
                SetPropertyChanged("_TASI");
            }
        }

However it seems that when the bool is changed from false to true, the image does not change. The value is changed via an async method:

public async void StartUpRoutine()
        {
            await Task.Run(() => PingServer());
            MessageBox.Show("Server Pinged");
        }

public void PingServer()
        {
            if (Directory.Exists(ServerAddress))
            {
                TASI = true;
                MessageBox.Show("Server Found");
            } 
            else
                TASI = false;
        }

I know the directory exists because the MessageBox is popping up showing "Server Found". But the DataTrigger isn't firing in my XAML. I can see the CloseImage but not the CheckImage. If I change it to false:

<DataTrigger Binding="{Binding TASI}" Value="False">

Then I see the CheckImage and not the CloseImage. So the Image Sources are set right, they just aren't changing when the value is changed in the ViewModel.

Answer 1

You are raising the PropertyChanged event for the wrong property name.

SetPropertyChanged("_TASI"); 

needs to be

SetPropertyChanged("TASI");

or better

SetPropertyChanged(nameof(TASI));