Caused by: java.util.zip.ZipException: error in opening zip file

[Houdini]

gtz is a directory with bunch of text files.
If I run classic wordcount example in ruby with streaming all is ok.

houdini@mozart:~/MyRuby/hadoop_test$ ruby wookomg_wordcount.rb --run=hadoop gtz gtz-outputI, [2010-09-10T05:06:49.898813 #30841] INFO -- : Launching hadoop!
I, [2010-09-10T05:06:49.898939 #30841] INFO -- : Running

/media/backup/hadoop-0.21.0/bin/hadoop \ jar /media/backup/hadoop-0.21.0/contrib/streaming/hadoop-streaming.jar \ -mapper '/home/houdini/.rvm/rubies/ruby-1.9.2-p0/bin/ruby /home/houdini/MyRuby/hadoop_test/wookomg_wordcount.rb --map ' \ -reducer '/home/houdini/.rvm/rubies/ruby-1.9.2-p0/bin/ruby /home/houdini/MyRuby/hadoop_test/wookomg_wordcount.rb --reduce ' \ -input 'gtz' \ -output 'gtz-output' \ -jobconf mapred.job.name='wookomg_wordcount.rb---gtz---gtz-output'

Exception in thread "main" java.io.IOException: Error opening job jar: /media/backup/hadoop-0.21.0/contrib/streaming/hadoop-streaming.jar

at org.apache.hadoop.util.RunJar.main(RunJar.java:130)
Caused by: java.util.zip.ZipException: error in opening zip file

at java.util.zip.ZipFile.open(Native Method)
at java.util.zip.ZipFile.(ZipFile.java:114)
at java.util.jar.JarFile.(JarFile.java:135)
at java.util.jar.JarFile.(JarFile.java:72)
at org.apache.hadoop.util.RunJar.main(RunJar.java:128)