Problem to using custome fonts in wpf

hello guys

I'm trying to use Material-Design-Iconic-Font font in my wpf app with this code:

<Label x:Name="label" Content="&#xf136;" FontFamily="./Fonts/#Material-Design-Iconic-Font" HorizontalAlignment="Left" Margin="435,112,0,0" VerticalAlignment="Top" FontSize="20" TextOptions.TextHintingMode="Animated"/>

in Visual Studio designer, label show X icon very well and there is no problem but when I run my app, its show me asquare!!!

what is the problem and how can I fix that?

tnx.

:)