How do I add items dynamically to a WrapPanel?

[Falkeli]

I have the following XAML:

<Window x:Class="ImageComparing.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Height="350" Width="525" xmlns:my="clr-namespace:ImageComparing" Title="Image comparing">
    <DockPanel>
        <ToolBar Name="toolbar1" DockPanel.Dock="Top" Height="41" Background="#FFA5D95A">
            other content
        </ToolBar>
        <WrapPanel Name="wrapPanel1" >
            other content
            <Label Content="Label" Height="28" Name="label1" />
        </WrapPanel>
    </DockPanel>
</Window>
 

I want to add content to wrapPanel1 - I tried the following code:

    if (info.Attributes == FileAttributes.Directory)
        wrapPanel1.Children.Add(new FolderEntry(info.Name));
    else
        wrapPanel1.Children.Add(new FileEntry(info.Name));
 

for some reason, the items don't show up. How can I fix that problem?

[Frinavale]

The items need to be WPF controls.
Does the FileEntry inherit from something like FrameworkElement?