Eclipse - java.lang.NoClassDefFoundError: com/sleepycat/je/DatabaseException

package com.x2iq.iqSearchDB;

import com.sleepycat.je.DatabaseException;

import com.sleepycat.je.Environment;

import com.sleepycat.je.EnvironmentConfig;

import java.io.File;

public class SentencesDB {

private Environment myDbEnvironment;

private String db_Base;

private String sentence;

private String root;

private int times;

private int total_level;

private int min_level;

private int max_level;

private int last_level;

private int bottom_node;

public SentencesDB() {

myDbEnvironment = null;

db_Base = "/usr/local/";

}

public void openDB() {

try {

EnvironmentConfig envConfig = new EnvironmentConfig();

envConfig.setAllowCreate(true);

myDbEnvironment = new Environment(new File("/usr/local/iq_data"), envConfig);

} catch (DatabaseException dbe) {

// Exception handling goes here

}

public void closeDB() {

try {

if (myDbEnvironment != null) {

myDbEnvironment.close();

}

} catch (DatabaseException dbe) {

// Exception handling goes here

}

Then I try to test it in the scrapbook with the following code:

SentencesDB db = new SentencesDB();

And I get this error:

java.lang.NoClassDefFoundError: com/sleepycat/je/DatabaseException

at CodeSnippet_3.run(CodeSnippet_3.java:4)

at org.eclipse.jdt.internal.debug.ui.snippeteditor.ScrapbookMain1.eval(ScrapbookMain1.java:20)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

at java.lang.reflect.Method.invoke(Method.java:585)

at org.eclipse.jdt.internal.debug.ui.snippeteditor.ScrapbookMain.evalLoop(ScrapbookMain.java:54)

at org.eclipse.jdt.internal.debug.ui.snippeteditor.ScrapbookMain.main(ScrapbookMain.java:35)

I do not understand why. The BerkeleyDB jar files are placed already in /System/Library/Java/Extensions and the class compiles correctly. Any idea on why it is not running? What am I forgetting?

Thanks in advance for your help,