我开始使用磨床工具，每当我运行我的脚本时，我都会收到以下错误。
ImportError: No module named net.grinder.script. Grinder
这是我要运行的脚本
# A minimal script that tests The Grinder logging facility.
#
# This script shows the recommended style for scripts, with a
# TestRunner class. The script is executed just once by each worker
# process and defines the TestRunner class. The Grinder creates an
# instance of TestRunner for each worker thread, and repeatedly calls
# the instance for each run of that thread.
from net.grinder.script.Grinder import grinder
from net.grinder.script import Test
# A shorter alias for the grinder.logger.info() method.
log = grinder.logger.info
# Create a Test with a test number and a description. The test will be
# automatically registered with The Grinder console if you are using
# it.
test1 = Test(1, "Log method")
# Instrument the info() method with our Test.
test1.record(log)
# A TestRunner instance is created for each thread. It can be used to
# store thread-specific data.
class TestRunner:
# This method is called for every run.
def __call__(self):
log("Hello World")
运行此脚本时，我会收到导入错误。
我也设置了 CLASSPATH 和 JAVA_HOME 环境变量。谁能帮我吗。