Firstly you've posted this in the TiVo section of the board, so it's good to check whether you're using a TiVo box or a V6. If you're not sure, check here - the C4 app itself is only available on the V6 box. TiVo has access to the same C4 "Video On Demand" content that V6 has, but doesn't have the app.
If this is not the problem, what's happening when you try to use the All-4 app on your V6? Do other apps work, such as ITV-Hub or BBC iPlayer?
I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more
Have I helped? Click Mark as Helpful Answer or use Kudos to say thanks