Why my CTA is not working

Call-To-Action or CTA is a piece of code including iframe. Iframe allows embedding CTA into webpages. If an iframe isn’t enabled on the website you want to show CTA, then CTA will not appear there. 
RetargetKit CTA identifies those sites and informs you if you can embed CTA to that link or not. Once you insert the link, it will leave you a message if that website does not allow iframes.