loadVars and another location

I have this piece of code from the flash help

var my_lv:LoadVars = new LoadVars();
my_lv.onLoad = function(success:Boolean) {
	if (success) {
		tekst.text = this.toString();
	} else {
		trace("Error loading/parsing LoadVars.");
	}
};
my_lv.load("http://www.helpexamples.com/flash/params.txt");

It works perfect if i preview and even when i place this swf in a webserver and look at it true the internet.

Now i want to change the adres so i try this

var my_lv:LoadVars = new LoadVars();
my_lv.onLoad = function(success:Boolean) {
	if (success) {
		tekst.text = this.toString();
	} else {
		trace("Error loading/parsing LoadVars.");
	}
};
my_lv.load("http://mrtn.1l.com/notdefined/GuestBook.php?action=read&r="+random(999)+"&NumLow=0");

This works well if i preview the movie, BUT NOT when i look at it when de swf is viewed trough the internet.

Can anyone help me with this ?
Thx for reading (and maybe make a usefull contribution :stuck_out_tongue: )