SAAJ, SOAP API problem

I have to create a new soap message from an existing file (attaching the file as the SOAP Attachment unchanged). I am just trying to get started at the moment and have downloaded the SAAJ from the sun web site:

https://saaj.dev.java.net/

I have included the downloaded jar files in my Java/lib folder and included it in my classpath. I am using Net Beans 5 and have also imported the 2 jar files (saaj-api.jar and saaj-impl.jar) to the project library.

I have the code for creating and manipulating the SOAP file but it is all commented out apart from these two lines:

MessageFactory messageFactory = MessageFactory.newInstance();

SOAPMessage message = messageFactory.createMessage();

I get the error:

Exception in thread "main" java.lang.NoClassDefFoundError: javax/activation/DataSource

at com.sun.xml.messaging.saaj.soap.ver1_1.SOAPMessageFactory1_1Impl.createMessage(SOAPMessageFactory1_1Impl.java:47)

at prototype.SOAPFunctions.SOAPRun(SOAPFunctions.java:40)

at prototype.Main.main(Main.java:32)

Can someone please help! I've imported the following to my project:

import javax.xml.soap.*;

import javax.xml.transform.*;

import java.io.FileInputStream;

import com.sun.xml.messaging.saaj.soap.ver1_1.SOAPMessageFactory1_1Impl;

import javax.xml.transform.stream.*;

import org.w3c.dom.*;

[1421 byte] By [mcab21a] at [2007-10-3 3:26:17]