关于Lotus与Servlet的古怪问题....%%%%%%%%%%%%%%%

[添翼软件]

操作系统：windows2000
开发环境：IBM visualage for java
代码：
import lotus.domino.*;
import java.io.*;
import java.util.*;

public class NotesConnections {
lotus.domino.NotesFactory notesfactory;
lotus.domino.Session session;
lotus.domino.Database db;
public NotesConnections(){
try {
notesfactory=new NotesFactory();
session = notesfactory.createSession("127.0.0.1","admin","password");\\此处错误
db=session.getDatabase(session.getServerName(),"names.nsf");
}
catch(NoClassDefFoundError e){
System.out.println(e);
System.out.println(e.getMessage());
}
catch(Exception e) {
System.out.println(e);
System.out.println(e.getMessage());
}
}
}
错误提示：
addin:agent printing:java.lang.NoClassDefFoundError:lotus/domino/cso/Session
运行环境：
Lotus\Domino 5.05
在servlet中通过NotesConnections notescon=new NotesConnections();调用。

这个类中未用到 lotus/domino/cso/Session
为什么会报这个错？？？