关于hibernate加锁的问题？大家进来看一下。
我使用hibernate访问ORACLE9i数据库，首先数据要分页然后要加悲观锁，语句如下：

String   hqlStr   =   "from   MessageEntity   mes   where   mes.messageChannel=:mcv ";
quMessage   =   session.createQuery(hqlStr);
quMessage.setLockMode( "mes ",   LockMode.UPGRADE_NOWAIT);
quMessage.setString( "mcv ",   mesChannel);
quMessage.setFirstResult(beginNumber);
quMessage.setMaxResults(numberOfEachPage);

运行是报如下错误：
17:20:57,453   INFO     [STDOUT]   Hibernate:   select   *   from   (   select   messageent0_.mid   as   mid0_,   messageent0_.MDATE   as   MDATE0_,   messageent0_.MCHANNEL   as   MCHANNEL0_,   messageent0_.MEMAIL   as   MEMAIL0_,   messageent0_.MTITLE   as   MTITLE0_,   messageent0_.MCONTENT   as   MCONTENT0_,   messageent0_.MREPLY   as   MREPLY0_,   messageent0_.MSTATUS   as   MSTATUS0_   from   MESSAGE   messageent0_   where   messageent0_.MCHANNEL=?   and   (messageent0_.MREPLY   is   null)   and   substr(messageent0_.MSTATUS,   1,   1)= '0 '   and   substr(messageent0_.MSTATUS,   2,   1)= '0 '   )   where   rownum   <=   ?   for   update   of   messageent0_.mid   nowait
17:20:57,515   WARN     [JDBCExceptionReporter]   SQL   Error:   904,   SQLState:   42000
17:20:57,515   ERROR   [JDBCExceptionReporter]   ORA-00904:   "MESSAGEENT0_ ". "MID ":   无效的标识符

我把分页的两句
quMessage.setFirstResult(beginNumber);
quMessage.setMaxResults(numberOfEachPage);
去掉就好了，难道hibernate分页就不能加锁了？
请高人指点。

这是MessageEntity  
public   class   MessageEntity   implements   Serializable   {

private   static   final   long   serialVersionUID   =   -9876321L;

private   String   mid;

private   Calendar   messageDate;

private   String   messageChannel;

private   String   messageEmail;

private   String   messageTitle;

private   String   messageContent;

private   String   messageReply;

private   String   messageStatus;

public   MessageEntity()   {
}

private   void   readObject(ObjectInputStream   ois)   throws   IOException,
ClassNotFoundException   {
ois.defaultReadObject();
}

private   void   writeObject(ObjectOutputStream   oos)   throws   IOException   {
oos.defaultWriteObject();
}

public   void   setMid(String   mid)   {
this.mid   =   mid;
}

public   void   setMessageDate(Calendar   messageDate)   {
this.messageDate   =   messageDate;
}

public   void   setMessageChannel(String   messageChannel)   {
this.messageChannel   =   messageChannel;
}

public   void   setMessageEmail(String   messageEmail)   {
this.m