Definitely a Java issue at this point and not AppGameKit it's self.
Did you try the options I wrote in my previous post?
In the meantime, here are a few other steps.
1. Uninstall your existing Java Development kit
2. Download the latest JDK from here http://www.oracle.com/technetwork/java/javase/downloads/index.html
3. Open an elevated command prompt (Run cmd as Administrator)
4. Using command prompt, navigate to your C:/Program Files/Java/jdk1.8.0_25/bin
5. Type in the following command
keytool -genkey -v -keystore FILENAMEHERE.keystore -alias YOURALIASHERE -keyalg RSA -keysize 2048 -validity 10000
6. Follow the commands that appear for creating your Alias and Alias Password; write these down, you'll need it later!
7. In AppGameKit, use the newly created keystore (it should be in the bin directory). Where it says keystore Alias and Password, type in the Alias and Password you had just created.
Robert Janes (Samu Games)
http://www.samugames.com/artifact