请问这个错误是怎么造成的阿？？

[blue_tina_]

<2002-6-6 下午09时02分58秒> <Error> <HTTP> <[WebAppServletContext(2223762,DefaultWebApp,/DefaultWebApp)] Servlet failed with Exception
java.lang.NoSuchMethodError
at com.order.chat.util.XMLConfig.addElement(Unknown Source:688)
at com.order.chat.util.XMLConfig.addElement(Unknown Source:757)
at jsp_servlet._chatroom.__insert._jspService(__insert.java:351)
at weblogic.servlet.jsp.JspBase.service(JspBase.java:27)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:265)
at weblogic.servlet.internal.ServletStubImpl.invokeServlet(ServletStubImpl.java:200)
at weblogic.servlet.internal.WebAppServletContext.invokeServlet(WebAppServletContext.java:2495)
at weblogic.servlet.internal.ServletRequestImpl.execute(ServletRequestImpl.java:2204)
at weblogic.kernel.ExecuteThread.execute(ExecuteThread.java:139)
at weblogic.kernel.ExecuteThread.run(ExecuteThread.java:120)

[middle]

The Class used in runtime is not the one in compile time. So when some one else invoke a method on this class, a NoSuchMethod Exception is thrown.

It often happens in the deployment of J2EE component.

[blue_tina_]

那我该怎么做才能使这个错误消失？？