php - what causes this error NS_ERROR_DOCUMENT_NOT_CACHED

Question

I'm using URLLoader in flex, but as i load a certain url, the connection is aborted (monitored using HTTPFox plugin in firefox). I simulate same instance on another server but it does not abort. When I checked HTTPFox content it has the following value:

Error loading content (NS_ERROR_DOCUMENT_NOT_CACHED)

I've been searching the net but there seemed to be no explaination why NS_ERROR_DOCUMENT_NOT_CACHED occurs. I just thought knowing why such error message appeared would solve why the connection is aborted.

Here is a part of the code of the sample i made to test on both of the servers that worked and did not that does the URLLoader.

private var UrlLoaderService : URLLoader = new URLLoader();

function initializeData():void
{
     var parameters : URLVariables = new URLVariables();
     var requests : URLRequest = new URLRequest();

     parameters.param1="param1";
     parameters.param2="param2";
     parameters.param3="param3";

     requests.data = parameters;
     requests.method = URLRequestMethod.POST;
     requests.url = "/sampletest/testrequest.php?antiCache="+Math.random();

     UrlLoaderService.addEventListener(Event.COMPLETE, successResult);
     UrlLoaderService.load(requests);
}