Is your Roku 4 listed under Devices in Account settings when you are in the website control page? Make sure you add your Roku 4 and link it to your account. If this has already been done, try rebooting your Simple device. You may also try the Simple.TV channel plugin within PLEX and see if this works.
Hope these tips help.
2xRoku2 XS,Roku1+SE,Logitech Revue GoogleTV,Raspberry Pi+XBMC,Mac Mini+EyeTV DVR+RabbitTV+PLEX+Kodi,TiVo Premiere,Sony BluRay+streaming apps,Equiso Android TV,FireTV,Nexus player,Simple.TV Local TV:QAM from ISP coax line. PLEX+unsupported apps