When you build and run the enumErrors code, you should get the following output in a message box.
Error as returned from validate(): Error Code : -1072898028 Error reason : Content for element 'review' is invalid according to the DTD/Schema. Expecting: price. Error location: /*[local-name()="books" and namespace-uri()="urn:books"]/book[2]/review[1] Errors Count : 2 Error items from the allErrors collection: ErrorItem[0] : reason: Content for element 'review' is invalid according to the DTD/Schema. Expecting: price. location: /*[local-name()="books" and namespace-uri()="urn:books"]/book[2]/review[1] ErrorItem[1] : reason: Content for element 'review' is invalid according to the DTD/Schema. Expecting: pub_date. location: /*[local-name()="books" and namespace-uri()="urn:books"]/book[3]/review[1]