HI Tony, I have a few questains to ask you : I tried using one of the files from the STDHEP EvT files that you put in the upenn server and i could not run the files. IT throws an Exception ie vector enumeration. I donot know how to run those files. I am trying to get the out put on the screen and used the System.out.println() command , the code compiled with out problems but the output did not appear on the screen. CAn i use the command DumpParticleHierarchy() to get the hierarchy of a particle ? i tried using it but it gave me an error when i was trying to compile the code. When i use the command getDaughters() it returns an output for some particles and for others it throws out an exception ie java analysis exception, i tried try and catch to get aroud it but failed. Is there a way to get around it ? When i delete a histogram form the code and put in a new one it still shows the old histogram and the new one is no were to be seen, i have to start a new job to see the new histogram, is there a way around this problem? If i change the code and compile a couple of times then after some time it throws an error Java-Lang. Exception. i have to close it and start all over again . IS there a reson why this happens. Thanks Maha