I believe you have already created a proxy in your test environment and you are trying to call the proxy that you have created.You should be using a URL in the below structure .
http://[host]/base_path/conditional_flow_path.
What I can see is that you are missing the base path in your request URL. Your URL should look something like this :http://mgm-test.apigee.net/**base_path** where base_path is the path which you gave while creating your proxy.
@Andrei Popescu , Ideally it should work. Do you still see an issue ? Let me know OrgName using “Ask An Expert” button on right side bar. Let me investigate.