If the Nudge code has been reported as not active on the page, it usually means that the code has not been placed on the page, or marked active inside your internal CMS.
The code checker will report any issues with formatting, load speed, and positioning on page. If you have been shown this warning by the Nudge checker, you have not put the code on page.
Please view the instructions on: https://ndg.io/installation/<your username>/ for installation instructions.
The only time where the code checker might report incorrectly, is if the website being checked aggressively blocks bots. If you believe this is the case, or believe the judgement is in error, please contact support.