That error is a very generic. Basically it means that NeoLoad was not able to use your JAVA code. It can be because of the content of your JAVA code (private instead of public) , the Class that is not found
or simply because the JAR or the Classes cannot be loaded at all.
Make sure that you called the fully qualified name of your Classes preceded by "Packages" like described in the NeoLoad documentation.
NeoLoad uses its own JAVA version. If you compile your JAVA classes with a higher JDK version compared to the one used by NeoLoad, it will not work. For example, in NeoLoad 5.0.xx, the JRE version used is a 1.7.xx. If you compile your code with a JRE 1.8.xx then you will get the error mentioned above. To avoid that issue, make sure to compile your JAVA code with the same JRE version used by NeoLoad or even older.
You can see the NeoLoad JRE version used in the NeoLoad log files accessible through the menu "Help-->Open logs folder..."
