Error executing the Java AS Application Client

I want to develop an Java AS application client and I'm following the tutorial from the SAP Help Portal Creating and Implementing the Application Client - Developing Java EE 5 Applications - SAP Library

I created everything - in the meanwhile 2 times ;-) - as described in the tutorial. Unfortunately without success at the end. Starting the ANT script at the end I always get the following error.

Buildfile: C:\APPS\SAPNWDS7.3-EHP1-SP15-PAT0005\workspace\CalculatorServiceClient\appclient_starter.xml

execute:

     [java] java.lang.NoClassDefFoundError: com/sap/engine/services/appclient/client/Launcher

     [java] Caused by: java.lang.ClassNotFoundException: com.sap.engine.services.appclient.client.Launcher

     [java]     at java.net.URLClassLoader$1.run(URLClassLoader.java:202)

     [java]     at java.security.AccessController.doPrivileged(Native Method)

     [java]     at java.net.URLClassLoader.findClass(URLClassLoader.java:190)

     [java]     at java.lang.ClassLoader.loadClass(ClassLoader.java:306)

     [java]     at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)

     [java]     at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

     [java] Could not find the main class: com.sap.engine.services.appclient.client.Launcher.  Program will exit.

     [java] Exception in thread "main"

     [java] Java Result: 1

BUILD SUCCESSFUL

I think I updated the script correctly as described at the end of the tutorial.

Any idea what I did wrong ?