When I install JBPM, I type ant install.demo on the command line. The following is displayed. what do I need to do to fix the problem.

download.eclipse:
[echo] Getting Eclipse ...
[get] Getting: http://download.eclipse.org/technology/epp/downloads/release/helios/R/eclipse-java-helios-macosx-carbon.tar.gz
[get] To: /Users/John/Downloads/jbpm/jbpm-installer/lib/eclipse-java-helios-macosx-carbon.tar.gz
[get] Error opening connection java.io.FileNotFoundException: http://download.eclipse.org/technology/epp/downloads/release/helios/R/eclipse-java-helios-macosx-carbon.tar.gz
[get] Error opening connection java.io.FileNotFoundException: http://download.eclipse.org/technology/epp/downloads/release/helios/R/eclipse-java-helios-macosx-carbon.tar.gz
[get] Error opening connection java.io.FileNotFoundException: http://download.eclipse.org/technology/epp/downloads/release/helios/R/eclipse-java-helios-macosx-carbon.tar.gz
[get] Can't get http://download.eclipse.org/technology/epp/downloads/release/helios/R/eclipse-java-helios-macosx-carbon.tar.gz to /Users/John/Downloads/jbpm/jbpm-installer/lib/eclipse-java-helios-macosx-carbon.tar.gz

BUILD FAILED
/Users/John/Downloads/jbpm/jbpm-installer/build.xml:138: Can't get http://download.eclipse.org/technology/epp/downloads/release/helios/R/eclipse-java-helios-macosx-carbon.tar.gz to /Users/John/Downloads/jbpm/jbpm-installer/lib/eclipse-java-helios-macosx-carbon.tar.gz