01-20 16:04:41.230: ERROR/AndroidRuntime(31818): java.lang.NoClassDefFoundError: com.google.gdata.client.calendar.CalendarService
01-20 16:04:41.230: ERROR/AndroidRuntime(31818):     at com.daesu.GoogleTestActivity.onCreate(GoogleTestActivity.java:28)

구글 Calendar랑 동기화를 하고 자 합니다.
어떻게 해야 해결을 할 수 있을 까요?
답변 부탁 드립니다.

소스
package com.daesu;

import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import com.google.gdata.client.*;
import com.google.gdata.client.calendar.*;
import com.google.gdata.data.*;
import com.google.gdata.util.AuthenticationException;
import com.google.gdata.util.ServiceException;

import android.app.Activity;
import android.os.Bundle;

public class GoogleTestActivity extends Activity {
 private static final String mLoginAddr = "";
 private static final String mPassword = "";
 
 CalendarService mService = null;
 URL  mPostURL = null;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mService = new CalendarService("GoogleCalendarTest"); <== 요기부분에서 에러 가 납니다..
        try {
         mService.setUserCredentials(mLoginAddr, mPassword);
          } catch (AuthenticationException e) {
            // Invalid credentials
            e.printStackTrace();
          }

          try {     
           mPostURL = new    URL( "http://www.google.com/calendar/feeds/default/private/full" );     
           } catch (MalformedURLException e) {           
           // TODO Auto-generated catch block          
           e.printStackTrace();
      
           }
..
...

    }
}