It's because of the old AIR version. Here's a link saying that the 'new' 3.9 now supports KitKat (Android 4.4.2): http://news.softpedia.com/news/Adobe-Air-with-Android-4-4-KitKat-Support-Out-Now-on-Google-Play-417056.shtml
Try updating your SDK AND your AIR on the phone.