Does mixin effect search result?

[Yonder]

I have created two custom node types, the nodes which is mixin can not  be 
retrieved , why?

public class SearchTest
{
    private static String configFile = "e:\\jackrabbitHome\\repository.xml";
    private static String localpath = "e:\\jackrabbitHome";

    public static void main(String[] args) throws Exception
    {
        Repository repository = getRepository(configFile, localpath);
        Session session = repository.login(new 
SimpleCredentials("admin","admin".toCharArray()));
        
        Tools.registerNamespaces(session);
        Tools.RegisterCustomNodeTypes(session.getWorkspace(), "test.cnd");
        
        Node root = session.getRootNode();
        Node file1 = root.addNode("first", "ocm:file1");
        setNode(file1);
        Node file2 = root.addNode("second", "ocm:file2");
        setNode(file2);

        session.save();
        
        Query q = 
session.getWorkspace().getQueryManager().createQuery("//element(*, ocm:file1)", 
Query.XPATH);
        QueryResult result = q.execute();
        if (result.getNodes().hasNext())
        {
            System.out.println("Nodes ocm:file1 Found! ");//can be found
        } else
        {
            System.out.println("Nodes ocm:file1 not exist");
        }

        q = session.getWorkspace().getQueryManager().createQuery("//element(*, 
ocm:file2)", Query.XPATH);
        result = q.execute();
        if (result.getNodes().hasNext())
        {
            System.out.println("Nodes ocm:file2 Found! ");
        } else
        {
            System.out.println("Nodes ocm:file2 not exist");//cannot be found!
        }
    }

    private static void setNode(Node node)
    {
        try
        {
            node.setProperty("jcr:encoding", "iso-8859-1");
            node.setProperty("jcr:mimeType", "text/plain");
            node.setProperty("jcr:lastModified", Calendar.getInstance());
            node.setProperty("jcr:data", new FileInputStream("test.cnd"));
        } catch (Exception e)
        {
            e.printStackTrace();
        }
    }

    private synchronized static Repository getRepository(String configfile, 
String localpath) throws RepositoryException
    {
        Repository repo = RepositoryImpl.create(RepositoryConfig.create(new 
InputSource(configfile), localpath));

        return repo;
    }
}

test.cnd:

<'jcr'='http://www.jcp.org/jcr/1.0'>
<'sv'='http://www.jcp.org/jcr/sv/1.0'>
<'xs'='http://www.w3.org/2001/XMLSchema'>
<'xml'='http://www.w3.org/XML/1998/namespace'>
<'nt'='http://www.jcp.org/jcr/nt/1.0'>
<'fn'='http://www.w3.org/2005/xpath-functions'>
<'ocm'='http://jackrabbit.apache.org/ocm'>
<'mix'='http://www.jcp.org/jcr/mix/1.0'>
<'rep'='internal'>

[ocm:file1] > nt:resource
[ocm:file2] > nt:resource mix


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