初学Hibernate，出现Dialect class not found错误，如何解决？

org.hibernate.HibernateException: Dialect class not found: net.sf.hibernate.dialect.FirebirdDialect
org.hibernate.dialect.DialectFactory.buildDialect(DialectFactory.java:81)
org.hibernate.dialect.DialectFactory.buildDialect(DialectFactory.java:42)
org.hibernate.cfg.SettingsFactory.determineDialect(SettingsFactory.java:378)
org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:110)
org.hibernate.cfg.Configuration.buildSettings(Configuration.java:1881)
org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1174)
HibernateTest.doGet(HibernateTest.java:17)
javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
org.apache.catalina.servlets.InvokerServlet.serveRequest(InvokerServlet.java:419)
org.apache.catalina.servlets.InvokerServlet.doGet(InvokerServlet.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

本人初学Hibernate，出现以上错误，是哪里出了问题？下面是我的hibernate.cfg.xml文件。望指教！
<?xml version='1.0' encoding='UTF-8'?>

<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory>
<property name="hibernate.dialect">net.sf.hibernate.dialect.FirebirdDialect</property>
<property name="connection.url">jdbc:firebirdsql:localhost/3050:d:/test/db/test.fdb</property>
<property name="connection.driver_class">org.firebirdsql.jdbc.FBDriver</property>
<property name="connection.username">sysdba</property>
<property name="connection.password">masterkey</property>

<property name="jdbc.fetch_size">50</property>
<property name="jdbc.batch_size">30</property>
<property name="show_sql">true</property>
<!-- Mapping files -->
<mapping resource="Customer.hbm.xml"/>
</session-factory>
</hibernate-configuration>

hibernate 的版本问题

解决了，的确是版本问题，我用的是Hibernate3.1.3，所以应该按照下面的设置
<property name="hibernate.dialect">org.hibernate.dialect.FirebirdDialect</property>
看来版本2和版本3有很大不同啊，谢谢