Want help in uploading file

hi,I am using org.apahce.commons.FileUpload api to upload file.three is no error when i compile the servlet class ,but when i run it .it give the error.at this situation what can i do?

java.lang.NoClassDefFoundError: org/apache/commons/io/output/DeferredFileOutputStream

org.apache.commons.fileupload.disk.DiskFileItemFactory.createItem(DiskFileItemFactory.java:179)

org.apache.commons.fileupload.FileUploadBase.createItem(FileUploadBase.java:500)

org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:367)

org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:116)

webtest.FileUpload.doPost(FileUpload.java:29)

javax.servlet.http.HttpServlet.service(HttpServlet.java:709)

javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

[850 byte] By [ovea] at [2007-10-3 2:29:57]