On the ita matrix site, i found the following two segment flight. But I can't find the same on expedia or any other travel website. It seems that the carrier 'SN BRUSSELS AIRLINES' is unavailable. I also contacted a local travel company but they are just as clueless as I m. Does anyone have suggestions on how/where I can book it?

Toronto (YYZ) to Brussels (BRU)

Deutsche Lufthansa AG 6585
OPERATED BY AIR CANADA

Deutsche Lufthansa AG 5595
OPERATED BY SN BRUSSELS AIRLINES