能运行HelloWorld但是不能运行Receive呢，提示：Exception in thread "main" java.lang.NoClassDefFoundError(60)

请问：
    我用JavaMail实现邮件接收客户端，设置好路径后（CLASSPATH中已加点并且可以运行HelloWorld），进入当前目录：D：\mail\Receive> javac Receive.java,编译生成class文件，但执行D：\mail\Receive> java Receive后，提示：Exception in thread "main" java.lang.NoClassDefFoundError：Receive<wrong name:Receivemail/Receive>...........
    我想问问各位前辈，为什么我能运行HelloWorld但是不能运行Receive呢，、
另设置路径如下：classpath=.;D:\JBuilderX\jdk1.4\lib;D:\JBuilderX\jdk1.4\lib\dt.jar;D:\JBuilderX\jdk1.4\lib\tools.jar;
                JAVA_HOME=D:\JBuilderX\jdk1.4
                path=D:\JBuilderX\jdk1.4\bin;