parseXML configured operation error

I got this error when trying to configure the parseXML configured operation. The XML adapter is version 4.2. The adapter is installed on AIX 4.3.3. The error message is:
“The adapter process was unaible to supply a set of valid values for the following reasons:
(018) Error while processing name space request “Adapter::Namespace::lookupValues”: java.lang.NoClassDefFoundError: com/wm/lang/xml/WMDocumentException”

(The namespace mapping tab is blank)