Error "MF_MEDIA_ENGINE_ERR_SRC_NOT_SUPPORTED" "0xC00D36C4" when trying to smooth streaming under windows phone 8

I'm creating a windows phone 8 application with visual studio and when I try to reproduce a smooth streaming video with PlayerReady Client SDK, it just says

"MF_MEDIA_ENGINE_ERR_SRC_NOT_SUPPORTED"  "0xC00D36C4"

If in the URL I provide a static existing .mp4 file somewhere in the internet, it just plays it ok, but when I try to reproduce certain smooth streaming URL I need to play, it just says that error.

My testing URL works when using it inside http://amsplayer.azurewebsites.net/ so it's a valid streaming video, but when using it inside my app, it just complains with said error.

Somewhere I read that I should try to compile my project in Release mode, but currently it's not really possible (without having to change many settings I wouldn't like to).

Any hint?

Greetings