求救servlet配置与运行问题～Tomcat5.0＋jdk1.5＋MyEclipse

我用的是Tomcat5.0＋jdk1.5＋MyEclipse＋SQLServer2000
写好servlet后编译总是找不到符号的问题！？
                                                                                          请各路高手帮助
编译错误如下：                                                                            谢谢啦！
SimpleServlet.java:27: 找不到符号
符号： 变量 request
位置： 类 com.wei.servlet.SimpleServlet
                this.doGet(request,response) ;
                           ^
SimpleServlet.java:27: 找不到符号
符号： 变量 response
位置： 类 com.wei.servlet.SimpleServlet
                this.doGet(request,response) ;
                                   ^
2 错误servlet原代码应该没有问题SimpleServlet.javapackage com.wei.servlet ;import java.io.* ;
import javax.servlet.* ;
import javax.servlet.http.* ;public class SimpleServlet extends HttpServlet
{
public void doGet(HttpServletRequest req,HttpServletResponse resp) throws IOException,ServletException
{
PrintWriter out = resp.getWriter() ;
out.println("<HTML>") ;
out.println("<HEAD>") ;
out.println("<TITLE>THE FIRST SERVLET</TITLE>") ;
out.println("</HEAD>") ;
out.println("<BODY>") ;
out.println("<H1>Hello World!!!</H1>") ;
out.println("</BODY>") ;
out.println("</HTML>") ;
out.close() ;
}
public void doPost(HttpServletRequest req,HttpServletResponse resp) throws IOException,ServletException
{
this.doGet(request,response) ;
}
};