Windows phone 8 custom font?

Question

Windows phone

There is an application for Windows Phone 8 (Silverlight). I put the font file LinBiolinum_RI.otf in the Assets\Fonts folder. Exposed Build Action to Content.
There is a button on the page, I set the font for it with the following line:
In Design Time, the emulator correctly displays this custom font, but as soon as I start the application, the font is not applied. Checked on the device and on the emulator. I also tried to convert to ttf and set different Build Actions, but it didn't help.
Many sites say that these steps are enough to use custom fonts in the application. Please tell me what I'm doing wrong.