Problem with IDataCursor on JServ (destroy method not found)

I am trying to send an XML document over HTTP from a custom class within my application. I generated the client code from within Developer and it works fine as a stand alone client. However, when I integrate it with my web application I get the following error:
java.lang.NoSuchMethodError
at com.wm.data.OldDataCursor.destroy(BasicData.java:756)

I have client.jar on my classpath.

Thanks for any help.