Cold environment, improper measurements/ improper mixing. The room temperature should be around 75*, the humidity level should be under 50%. Scrape over the surface using a putty knife to remove any soft Epoxy then Sand surface lightly with 200 to 220 grit sandpaper. After sanding the clean surface with denatured or rubbing alcohol using a soft lint-free type cloth to remove any dust or sanding debris. After alcohol dries you're ready for a new flood coat.