http://msftplayground.com/2014/04/warm-up-form-based-web-application/

When I run the script in PowerShell command window, it works. However, it does not work when I run the script as the scheduler task. Any method to resolve it?
seems "$Browser.visible=$false;" is not working when the script is running as scheduler task.

Or any other good suggestion for SharePoint 2013 warm up script with FBA? Thanks.