why isnt my samsung j3 android phone sharing cast

[Android Central Question]

when i try to cast youtube fom my phone to my smart tv it
wont show the casting symbol

 

[Rukbat]

What are you casting TO? A Chromecast dongle? Another type of dongle connected to the TV? (The only "nothing additional needed" "casting" method is a Samsung phone doing screen mirroring to a Samsung Smart TV. If it's not, you'll need something plugged into the TV [into one of the HDMI inputs] to receive the "cast".)