windows phone 8.1 - Font loading correctly design time but not runtime (WP8.1) -

in project, have bunch of icons provided in custom icon font (a .ttf file). need show these on windows phone 8.1 app.

i've included font file in project, , defined static resource

<!-- fonts.xaml --> <resourcedictionary>     <!-- ... -->     <fontfamily x:key="icons">         /resources/fonts/custom_icons.ttf#custom_icons     </fontfamily> </resourcedictionary> 

as merged app's resource dictionary

<!-- in app.xaml --> <application.resources>     <resourcedictionary>         <resourcedictionary.mergedictionaries>             <!-- ... -->             <resourcedictionary source="resources/styles/fonts.xaml" />         </resourcedictionary.mergedictionaries>     </resourcedictionary> <application.resources> 

and when want include icon,

<textblock fontfamily="{staticresource icons}" fontsize="30">     &#xf0d5; </textblock> 

in design time (e.g. blend or vs visual editor), icon shows ok, when run app in emulator, rectangle indicates missing character.

i think there's problem font file - icons font awesome included same way work expected - have no idea how troubleshoot further.

what cause this? if need change font (i.e. ask designers change something), should change?