java.lang.NoClassDefFoundError: com/skype/SkypeException

I create a class SkypeTest when I have a function that return the version of my Skype. I user the Skype-java-api, and Mybuildpath is correctly configured.

When I create a web service, I got that errors.

IWAB0398E Error in generating WSDL from Java:  java.lang.NoClassDefFoundError: com/skype/SkypeException
    java.lang.NoClassDefFoundError: com/skype/SkypeException
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Unknown Source)
    at java.lang.Class.getDeclaredMethod(Unknown Source)
    at org.apache.axis.description.JavaServiceDesc.loadServiceDescByIntrospection(JavaServiceDesc.java:874)
    at org.apache.axis.description.JavaServiceDesc.loadServiceDescByIntrospection