Is your build script to the root of your projet ? If it isn't, have you changed the basedir property of the <project> element to point the root of your project.
I had myself problems of NoClassdefFound with classpath and axis Ant tasks. I wrote a script with an embeded classpath property like : <axis-java2wsdl output="${service.ws.dir}/${service.wsdl}" location="${service.location}" namespace="${service.nsmapping}" namespaceimpl="${service.nsmapping}" classname="${service.package}.${service.name}" implclass="${service.package}.${service.name}SoapBindingImpl"> <classpath> <pathelement location="${bin.dir}" /> <path refid="axis.classpath" /> <path refid="tomcat.classpath" /> </classpath> <mappingset> <mapping namespace="${service.nsmapping}" package="${service.package}" /> </mappingset> </axis-java2wsdl> It works for me.