jdo query problem

Getting  on the line java.lang.NullPointerException error on code line Query q = pm.newQuery(Employee.class);

public String getEmployee() {

        String returnRes = null;

        Query q = pm.newQuery(Employee.class);
        q.setFilter("lang == langParam");
        q.setOrdering("name");
        q.declareParameters("String langParam");

        try {
            List <Employee> results = (List<Employee>) q.execute("java");
            if (! results.isEmpty()) {
                for (Employee employee : results) {
                    returnRes = employee.getLang();

                }
            } else {
                returnRes = "nothing to return";
            }
            return returnRes;

        } finally {
            // TODO: handle exception
            q.closeAll();
            pm.close();
        }

    }


//Employee.java

package com.versefeed.setup;

import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.NotPersistent;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;

import com.google.appengine.api.datastore.Key;

@PersistenceCapable
public class Employee {

    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    private Key key;

    @Persistent private String name = "david";
    @Persistent private String lang = "java";
    @NotPersistent private int age = 26;

    //@Persistent private ContactInfo contactInfo;

    public Employee(String name, String lang) {
        this.name = name;
        this.lang = lang;
    }


    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getLang() {
        return lang;
    }

    public void setLang(String lang) {
        this.lang = lang;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Key getKey() {
        return key;
    }



}

//stacktrace
WARNING: /persistpojo
java.lang.NullPointerException
    at com.versefeed.setup.PersistPojo.getEmployee(PersistPojo.java:45)
    at com.versefeed.setup.PersistPojo.doGet(PersistPojo.java:78)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)