Chwk River

Hi all... I don't have cable or satellite TV but I bought sub to NHL TV that I watch via "Apple TV". I can watch some Canuck games but tonite is a "blackout". WTH? Can usually get the Sat nite games as part of Hockey nite in Canada and sometimes there's a "free game" ... I thought they'd all be "free" to a subscriber, but apparently they're not. I find the system annoying and confusing. Any chance someone here could explain how this NHL TV subscriber thing works and why I can't watch the game tonite as they visit the Ducks but other times I can watch home games - like when they hosted LA on Wed? Thanks!