WPF why my ObservableCollection object collection not update my ProgressBar - wpf

Question

i have WPF application and i am using PcapDotNet DLLs to send packets through the Networkcard.
This is my object that represent Wireshark file:
public class WiresharkFile
{
public event PropertyChangedEventHandler PropertyChanged;
virtual public void NotifyPropertyChange(string propertyName)
{
var handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propertyName));
}
private string _file; // file path
private string _packets; // how many packet in file
private string _sentPackets; // how many packet sent
private string _progress; // percentage (_sentPackets/_packets) * 100
public int Progress
{
get { return _progress; }
set
{
_progress = value;
NotifyPropertyChange("Progress");
}
}
public void Transmit(WireshrkFile)
{
// here i am send the packets
}
}
My list that hold this objects:
public ObservableCollection<WireshrkFile> files{ get; set; }
As you can see in every file that in process i am calculate the Progress.
Now all my files is inside ListView and in this ListView i have Progress-Bar column.
This is my Progress-Bar style:
<!-- Progress-Bar style -->
<Style x:Key="CustomProgressBar" TargetType="ProgressBar" >
<Setter Property="Template" >
<Setter.Value>
<ControlTemplate TargetType="ProgressBar">
<Border BorderBrush="Transparent" BorderThickness="1" Background="LightGray" CornerRadius="0" Padding="0" >
<Grid x:Name="PART_Track">
<Rectangle x:Name="PART_Indicator" HorizontalAlignment="Left" Fill="#FF15669E" />
</Grid>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Progress-Bar definition inside my ListView
<ListView.Resources>
<DataTemplate x:Key="MyDataTemplate">
<Grid Margin="-6">
<ProgressBar Name="prog" Maximum="100" Value="{Binding Progress}"
Width="{Binding Path=Width, ElementName=ProgressCell}"
Height="20" Margin="0" Background="#FFD3D0D0" Style="{StaticResource CustomProgressBar}" />
<TextBlock Text="{Binding Path=Value, ElementName=prog, StringFormat={}{0}%}" VerticalAlignment="Center"
HorizontalAlignment="Center" FontSize="11" Foreground="Black" />
</Grid>
</DataTemplate>
<ControlTemplate x:Key="ProgressBarTemplate">
<Label HorizontalAlignment="Center" VerticalAlignment="Center" />
</ControlTemplate>
</ListView.Resources>
So when the Wireshark file is in process i can see that it send the packets and the properties changing but the Propress-Bar is still with 0%.
So i made i little test and inside timer event click changed my WireshakFile Progress property and in this case i can see the my ListView Progress-Bar changing.
So my question is what i am doing wrong ?
Edit:
I also try something that looks very strange but this is woking:
Inside my Timer_Tick i try to loop over my ObservableCollection collection:
foreach (WiresharkFile item in files)
{
item.Progress = item.Progress;
}
As you can see it only make pointer to the same property but this is working.