The polling is sent after selection to wait for everything to be calculated on the Engine side. If you constantly get these messages it indicates that either the calculation takes a very long time to perform or that the script gets stuck and never will get the proper response (due to an invalid selection sequence or similar in the script).
To know what is going on I suggest you to first of all check so there is nothing missing in the script (selections in charts existing in containerobjects need the containerid as well for example). Secondly run the script from the jmeter GUI to see at what point the script gets stuck with polling and look into what the request before the poll contains and what the responses from that and the polls are.
To do so, right click on your script in the execution pane and select open in jmeter. Once opened enable the greyed out component "View results tree" and run the script. As the script is running the result tree will allow you to look at all requests ands responses sent when running the script.
