Error #2007 and PHP

Question

Hello!
Could you please help me with the following code because I can't find the solution - I receive Error #2007: Parameter text must be non-null. (I know what the error means but  I'm not experienced enough to handle it)
This is hit counter that uses AS3, PHP ("Counter.php") and  text file ("hit_count.txt").
AS3:
var variables:URLVariables = new URLVariables();
var varSend:URLRequest = new URLRequest("Counter.php");
varSend.method = URLRequestMethod.POST;
varSend.data = variables;
var varLoader:URLLoader = new URLLoader;
varLoader.dataFormat = URLLoaderDataFormat.VARIABLES;
varLoader.addEventListener(Event.COMPLETE, completeHandler);
// this is the part that causes problem:
variables.requestCode = "homepage";
varLoader.load(varSend);
function completeHandler(event:Event):void {
    var countVar = event.target.data.phpCountVar;       
PHP ("Counter.php"):
<?php
if ($_POST['requestCode'] == "homepage") {
    $txtDatabase = "hit_count.txt";
    $currentNumber = file_get_contents($txtDatabase, true);
    $fh = fopen($txtDatabase, 'w') or die ("cannot open file");
    $newNumber = $currentNumber + 1;
    $data = "$newNumber";
    fwrite($fh, $data);
    fclose($fh);
    print "phpCountVar=$newNumber";
?>
text file ("hit_count.txt"):
0
Any ideas?

Answer 1

click file/publish settings/flash and tick "permit debugging".  retest.  the problematic line number will be in your error message.
if that info doesn't allow to solve your problem, copy and paste the problematic line of code here.