Why Is CNN's Approval Rating For Trump 15 Points Lower Than Rasmussen's?

So As I Was Making This video Some Really Strange Things Were Happening To The Show…
https://www.youtube.com/watch?v=pblQ5tQx8v4
https://www.zerohedge.com/news/2018-02-27/why-cnns-approval-rating-trump-15-points-lower-rasmussens