Open local html file with parameters in default browser

I am trying to open a local HTML file in the default browser from AIR, while passing parameters.

var source:File = File.documentsDirectory;

  source = source.resolvePath("test.html");

  var url:String = source.url+"?";

  var urlVars:URLVariables = new URLVariables(); 

  urlVars.var1="One"; 

  urlVars.var2= "Two";

  var request:URLRequest = new URLRequest(url);

  request.data = urlVars;

  navigateToURL(request);

This works fine in debugger. It opens the default browser and the url contains the parameters.

However, when the app is published and installed, the page opens in the default browser But With No Parameters.

Some security setting no doubt.

Any help appreciated.