Hy ! I'm working with VisAD now for about 3 weeks and I am really enjoyed about it. I have following problem: I want to have a VisADSlider on my display. So i construct e.g. a RealType and a Scalarmap: RealType x = new RealType("x", null, null); Scalarmap scm = new Scalarmap(x, Display.SelectValue); The VisADSlider is constructed the following way: VisADSlider vslider = new VisADSlider(scm, 0.0f, 1.0f); Above line throws a NullpointerException. If I print out the stacktrace for this NullpointerException I get no further information. The Exceptionmessage is: java.lang.NullpointerException at myclass.main(Compiled Code) I wrote a simple program, constructing a RealType, a Scalarmap, the Slider and a Frame to display the Slider. ?? My working platform is Linux with Kernel 2.0.36 and the latest releases of jdk1.2 and java3d from www.blackdown.org. I didn't have any problems with VisAD on Linux. Compilation was no problem and i wrote some small RMI applications, 3D Visualizations of functions over regular, irregular grids, ... Thanks, for every reply, Mike.