Error #2007: Parameter text must be non-null

[basement]

I'm using a code to random show a quote and works fine however I'm getting an error:

TypeError: Error #2007: Parameter text must be non-null.
at flash.text::TextField/set text()
at quotes_fla::MainTimeline/rotateQuote()
at flash.utils::Timer/flash.utils:Timer::_timerDispatch()
at flash.utils::Timer/flash.utils:Timer::tick()

The code I'm using is:

import caurina.transitions.Tweener;

var quote:Array = new Array();
var totalQuotes:Number;
quoteMC.alpha = 0;

var rotateTimer:Timer = new Timer(5000, 100);//rotates the quote every 2 seconds for 100 times
rotateTimer.addEventListener("timer", rotateQuote);//add a listener to the timer
rotateTimer.start();// start the timer

function init():void {
    var quotesXML:XML = new XML();
    quotesXML.ignoreWhitespace = true;
    var XMLURL:URLRequest = new URLRequest("flash/quotes1.xml");
    var myLoader:URLLoader = new URLLoader(XMLURL);
    myLoader.addEventListener("complete", xmlLoaded);
    function xmlLoaded(event:Event):void {
        quotesXML = XML(myLoader.data);
        totalQuotes = quotesXML.quote.length();
        for (var i:int = 0; i < quotesXML.quote.length(); i++) {
            quote[i] = quotesXML.quote[i].text;
        }
        var initRandom:Number = randomNumber(0, totalQuotes);
        Tweener.addTween(quoteMC, {alpha:1, time:5});
        quoteMC.quote_txt.text = String(quote[initRandom]);
    }
    
}

function rotateQuote(evt:TimerEvent) {
    quoteMC.alpha = 0;
    Tweener.addTween(quoteMC, {alpha:1, time:5});
    quoteMC.quote_txt.text = "";
    var randomness:Number = randomNumber(0, totalQuotes);
    quoteMC.quote_txt.text = quote[randomness];
}

function randomNumber(low:Number, high:Number):Number {
    var low:Number = low;
    var high:Number = high;
    return Math.round(Math.random() * high - low) + low;
}
init();

I couldn't find a similar code to understand why it's wrong.
I'm totally new at as3 so any help will be welcome.
Thanks in advance.

BTW, the error only shows at IE, in Firefox it seems ok.

[basement]

If there is anybody trying to help, the original code is from Tiago's Blog: http://blog.six4rty.ch/tutorials/fla...quote-rotator/

And when I debugged it, the error pops up at line 35:

quoteMC.quote_txt.text = quote[randomness];

thanks

[creynders]

The Timer object immediately sends a "timer" event, which means that it's listener ("rotateQuote") is executed before the XML has finished loading.
In this case the function "randomNumber" returns a number between 0 and 0
so, the error-throwing line is translated to:
quoteMC.quote_txt.text = quote[0];
but since the XML hasn't loaded yet "quote" is empty so it returns "null"
thet "text" property of the TextField doesn't accept "null" as a value, hence the error

[basement]

Great explanation creynders, even for me that I'm new at this.

I didn't though this could be the problem because it was actually working. Thinking about it: the error pops up at random, so maybe it was that when the "rotate" and "Tweener" sync at a specific interval, just then the error appear??

Anyway, in another forum they suggest me the following trick:

quoteMC.quote_txt.text = quote[randomness]||"";

And it actually worked.

Thanks.

[creynders]

It worked, because it's a solution for the problem I described.

What you're writing there is a conditional assignment it means (roughly translated) if quote[randomness] translates to nothing then take the value "" (which is just an empty string)

The reason why it seems to randomly popup is because sometimes the xml will have loaded before the function is executed and sometimes not.