nodeForXPath不返回任何节点：TouchXML

NSMutableArray *res = [[NSMutableArray alloc] init];
NSData* valueData=[value dataUsingEncoding:NSUTF8StringEncoding];

    // Do something with the CXMLDocument* result
    CXMLDocument *result = [[[CXMLDocument alloc] initWithData:valueData options:0 error:nil] autorelease];

    NSArray *nodes = NULL;


    nodes = [result nodesForXPath:@\"//Outputs\" error:nil];

    NSLog (@\"Nodes is %@\\n\", nodes);

    for (CXMLElement *node in nodes) {
        NSLog (@\"Test\");
        NSMutableDictionary *item = [[NSMutableDictionary alloc] init];
        int counter;
        NSLog (@\"Child Count is %@\\n\",[node childCount]);
        NSLog (@\"Child node is%@\\n\",[[node childAtIndex:0] stringValue]);
        for(counter = 0; counter <= [node childCount]; counter++) {
            //  common procedure: dictionary with keys/values from XML node
            [item setObject:[[node childAtIndex:counter] stringValue] forKey:[[node childAtIndex:counter] name]];


        }


        //[item setObject:[[node attributeForName:@\"id\"] stringValue] forKey:@\"id\"];  

        [res addObject:item];
        [item release];
    }

    //  and we print our results
    NSLog(@\"%@\", res);
    [res release];


}

    <Nodes>
    <Inputs>
        <name>TestProgram</name>
        </Inputs>
        <Outputs>
            <ReturnCode>0</ReturnCode>
            <ReturnMessage>Success</ReturnMessage>
            <NameDetails attr1=\"value1\">Test Program</NameDetails>
            <NameInstance attr1=\"value1\">
            <NameCharacteristics>
                <Dob>04-25-2011</Dob>
            </NameCharacteristics>
            </NameInstance>
        </Outputs>
</Nodes>