The URL which you mentioned is to call the integration server but not to launch PI
To launch PI home page : http://host:port/dir/start/index.jsp
If your requirement is to connect to the integration server then, make sure that 50000 is a valid port.
Your port should be like 5<<system number>>00.
You can even try accessing the home page "http: //host: port/ dir/start/ index.jsp" to see if the PI development system is up and running.