I am new to java web start. I am trying to put my jar on the server. I got the JARSigningException exception. I used jarsigner to sign the jar file and test it should be ok "verified". However I still get the JARSigningException exception. The strange thing is My college tried it from his unix system, it works. Please could anybody kindly help and advise. I am setting java 1.6, for compile and execute in my Eclipse. However it import jre7 by default (the highest jre version on my laptop) by default. Does this cause problem?