You probably mean the Deezer app in the SmartTV part of the Bsys4 (?) As you may have noticed with the other apps there, this platform is obsolete….basicly no longer working. In order to get Deezer  to play on the BSys4, you will need an external device connected there with the Deezer app installed e.g. an AppleTV, a GoogleTV/Chromecast……. Another way is to have a NetworkLinked B&O device in the setup, start playback of Deezer there and then Join in on the BSys4. Using an Essence MK2 or the Core integrated with the BSys4 would even give you Deezer as a selectable source in the menu of the BSys4. MM  

Thanks Millemissen for confirming.  And yes I meant the internal app.   I kind of wondered but really thought I saw it try to connect at one point when setting everything up.  The Moment has no problem connecting to Deezer so I was optimistic it could still but, as you pointed out, it's easy enough to link it to the Moment or one of the cores, etc.