运行master的Spark ClassNotFoundException

我已经下载并使用了Spark 0.80 sbt/sbt assembly.它很成功.但是./bin/start-master.sh,在日志文件中看到运行时出现以下错误

Spark Command: /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/bin/java -cp :/shared/spark-0.8.0-incubating-bin-hadoop1/conf:/shared/spark-0.8.0-incubating-bin-hadoop1/assembly/target/scala-2.9.3/spark-assembly-0.8.0-incubating-hadoop1.0.4.jar
/shared/spark-0.8.0-incubating-bin-hadoop1/assembly/target/scala-2.9.3/spark-assembly_2.9.3-0.8.0-incubating-hadoop1.0.4.jar -Djava.library.path= -Xms512m -Xmx512m org.apache.spark.deploy.master.Master --ip mellyrn.local --port 7077 --webui-port 8080

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/spark/deploy/master/Master
Caused by: java.lang.ClassNotFoundException: org.apache.spark.deploy.master.Master
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:247)

更新:执行sbt clean后(根据以下建议)它正在运行:请参阅屏幕截图.