java.lang.NoClassDefFoundError, msg=oracle/apps/xdo/template/XDOException

I am getting this error when trying to print pdf file using the method DocumentHelper.exportDocument().

DocumentHelper.exportDocument(
               pageContext,
               "PER",
               "TMTESTPRINT",
               isoLan,
               isoTer,
               result.getInputStream(),
               "PDF",
               null);

              DocumentHelper.exportDocument(
               pageContext,
               "PER",
               "TMTESTPRINT",
               isoLan,
               isoTer,
               result.getInputStream(),
               "PDF",
               null);