Executing thread groups separately in jmeter

I have 2 thread groups in my test case. Group A should complete first before Group B starts to execute(at least I though this was the way it worked).

Unfortunately they are firing at the same time and tests from both tread groups are executing, what can I do to prevent this from happening. Not to allow group B to start before 开发者_开发问答group A is done executing?

Go to the test plan element and check the box "Run Thread Groups consecutively". This will give you what you want.

http://jmeter.apache.org/usermanual/component_reference.html#Test_Plan