Something missing to display images ? [XAML][C#]

Question

I wrote a file browser in XAML/C#.

Files are listed in a listView

<ListView Margin="230,0,0,0" Name="listViewContent" ItemsSource="{Binding ContentCollection}">
        <ListView.View>
            <GridView>
                <GridViewColumn Header="Title" Width="290">
                    <GridViewColumn.CellTemplate>
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal">
                                <Image Source="{Binding Image}" Height="15" Width="15"/>
                                <TextBlock Text="{Binding Title}" />
                            </StackPanel>
                        </DataTemplate>
                    </GridViewColumn.CellTemplate>
                </GridViewColumn>

When the collection is populate, I get the state of each files, in order to know those that are locked : (method from the item class)

public void GetState()
    {
        try
        {
            // Get the stateInfo
            StateInfo stateInfo = iStateInfoService()).GetStateInfo(itemID);

            // Check if the file is locked
            if (stateInfo.IsLocked)
            {
                if (stateInfo.UserName == tConnectionInfoSingleton.Instance().Username)
                {
                    Image = MyRessourceDictionnary["KeyImage"] as BitmapImage;
                }
                else
                {
                    Image = MyRessourceDictionnary["LockImage"] as BitmapImage;
                }
            }
        }
        catch (Exception)
        {

        }
    }

Here are the lines in the RessourceDictionnary :

<BitmapImage x:Uid="KeyImage"      x:Key="KeyImage"      UriSource="Images/Key.png"/>
<BitmapImage x:Uid="LockImage"     x:Key="LockImage"     UriSource="Images/Lock.png"/>

Everything works fine on my computer. But it fails on 2 other computers. It doesn't fail when there is no locked file.

I don't understand why it works on my computer and doesn't on others.

My project is compiled with .Net 3.0. On every comuter, .Net 3.5 SP1 is installed.

Is there something missing ?