Installing Agile BI on PDI Kettle - Spoon 5.0.1-stable

HI,

I am trying to install the agile BI plugin on the last version of PDI Kettle - Spoon 5.0.1-stable
I have downloaded it from ftp://download.pentaho.org/client/agile-bi/ (I have tried will all versions found there)
The instructions for PDI-4.0.0-stable say to unzip it on data-integration/plugins/spoon but I don't have any spoon directory.

Anyway I have unzipped it on data-integration/plugins/ but spoon gives and error:
/opt/data-integration
2014/02/04 09:14:11 - General - ERROR (version 5.0.1-stable, build 1 from 2013-11-15_16-08-58 by buildguy) : Error starting Spoon shell
2014/02/04 09:14:11 - General - ERROR (version 5.0.1-stable, build 1 from 2013-11-15_16-08-58 by buildguy) : java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory
2014/02/04 09:14:11 - General - at org.pentaho.agilebi.spoon.perspective.AbstractPerspective.<init>(AbstractPerspective.java:53)
2014/02/04 09:14:11 - General - at org.pentaho.agilebi.spoon.perspective.AgileBiVisualizationPerspective.<init>(AgileBiVisualizationPerspective.java:62)
2014/02/04 09:14:11 - General - at org.pentaho.agilebi.spoon.perspective.AgileBiVisualizationPerspective.<clinit>(AgileBiVisualizationPerspective.java:56)
2014/02/04 09:14:11 - General - at org.pentaho.agilebi.spoon.AgileBiSpoonVisualizationPlugin.getPerspective(AgileBiSpoonVisualizationPlugin.java:38)
2014/02/04 09:14:11 - General - at org.pentaho.di.ui.spoon.SpoonPluginManager.loadPlugin(SpoonPluginManager.java:95)
2014/02/04 09:14:11 - General - at org.pentaho.di.ui.spoon.SpoonPluginManager.<init>(SpoonPluginManager.java:72)
2014/02/04 09:14:11 - General - at org.pentaho.di.ui.spoon.SpoonPluginManager.<clinit>(SpoonPluginManager.java:63)
2014/02/04 09:14:11 - General - at org.pentaho.di.ui.spoon.Spoon.init(Spoon.java:802)
2014/02/04 09:14:11 - General - at org.pentaho.di.ui.spoon.Spoon.createContents(Spoon.java:8641)
2014/02/04 09:14:11 - General - at org.eclipse.jface.window.Window.create(Window.java:426)
2014/02/04 09:14:11 - General - at org.eclipse.jface.window.Window.open(Window.java:785)
2014/02/04 09:14:11 - General - at org.pentaho.di.ui.spoon.Spoon.start(Spoon.java:8672)
2014/02/04 09:14:11 - General - at org.pentaho.di.ui.spoon.Spoon.main(Spoon.java:625)
2014/02/04 09:14:11 - General - at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2014/02/04 09:14:11 - General - at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
2014/02/04 09:14:11 - General - at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
2014/02/04 09:14:11 - General - at java.lang.reflect.Method.invoke(Method.java:601)
2014/02/04 09:14:11 - General - at org.pentaho.commons.launcher.Launcher.main(Launcher.java:134)
2014/02/04 09:14:11 - General - Caused by: java.lang.ClassNotFoundException: org.slf4j.LoggerFactory
2014/02/04 09:14:11 - General - at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
2014/02/04 09:14:11 - General - at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
2014/02/04 09:14:11 - General - at java.security.AccessController.doPrivileged(Native Method)
2014/02/04 09:14:11 - General - at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
2014/02/04 09:14:11 - General - at java.lang.ClassLoader.loadClass(ClassLoader.java:423)
2014/02/04 09:14:11 - General - at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
2014/02/04 09:14:11 - General - at org.pentaho.di.core.plugins.KettleURLClassLoader.loadClass(KettleURLClassLoader.java:98)
2014/02/04 09:14:11 - General - at java.lang.ClassLoader.loadClass(ClassLoader.java:356)
2014/02/04 09:14:11 - General - ... 18 more
stopping

Any idea how to proceed? Thank you

Best regards