The invalid answer pops up because in the form view there is no text field chosen for verification. As nearly as I can tell, you aren't using a result slide, or passing a score to any other slide; You have written triggers that verify the answers, and show the Correct or Incorrect layer; the Form View of the quiz slide is entirely blank - you aren't using any of the built-in quiz functions. You don't need to have a quiz slide, but if you get rid of it, you may have to recreate the Correct and Incorrect layers. So just get rid of the "Submit interaction when user clicks Verify button", and use the triggers you have already created.