Casting Cartoon HD via Avia on Galaxy Tab 3?

[Angel343]

Hi
After searching how to cast Cartoon HD on Chromcast I have bought Avia, have it all set up etc. The issue I am having is when I choose a video to watch on Cartoon HD (after connecting Chromecast and Avia), I press Custom and the only option is Video Player and Photos. The video player is just to watch it on the tablet. I thought Avia would come up as an option. Is there something I need to change in my settings as I cannot find a fix. Just to add the usual Apps work so I know the Chromecast is working ie Netflix.

Thanks in advance.