java.lang.ExceptionInInitializerError with gephi application

I am trying to make a graphic with gephi, i have used this code before and it worked but now i'm in a web application and it is not. When i run my code i get a java.lang.ExceptionInInitializerError on the line:

ProcessingTarget target =(ProcessingTarget) previewController .getRenderTarget(RenderTarget.PROCESSING_TARGET);

when i broke the line down the error was thrown on the parameter, so i replaced it with "processing" which is the value that constant returned.I still get the same error on that line.