I think that I'm having the same problem. When running this code:
def ant = new AntBuilder();
ant.unzip( src, dest, overwrite:"true");
I get:
java.lang.NoClassDefFoundError: org/apache/tools/ant/BuildException
I've uploaded ant.jar and ant-launcher.jar, and checked them under the 'Jars' tab.
I don't have the option of putting these classes into the classpath, since this if for a runtime.
I'm on ScriptMaster 4.124, FMPA 11.0v4, Mac OS 10.6.8, and Ant 1.8.2
Any help or advice is appreciated
Roger