Noobslide-Skript einfaches alert einfügen funktioniert nicht

[icke]

Hallo liebes Forum,

ich versuche mich zur Zeit mit dem Noobslide-Script von hier - speziell mit dem 6ten Beispiel.

Das eigentliche JavaScript sieht so aus:

var noobSlide = new Class({  
  
	initialize: function(params){  
		this.items = params.items;  
		this.mode = params.mode || 'horizontal';  
		this.modes = {horizontal:['left','width'], vertical:['top','height']};  
		this.size = params.size || 240;  
		this.box = params.box.setStyle(this.modes[this.mode][1],(this.size*this.items.length)+'px');  
		this.button_event = params.button_event || 'click';  
		this.handle_event = params.handle_event || 'click';  
		this.onWalk = params.onWalk || null;  
		this.currentIndex = null;  
		this.previousIndex = null;  
		this.nextIndex = null;  
		this.interval = params.interval || 5000;  
		this.autoPlay = params.autoPlay || true;  
		this._play = null;  
		this.handles = params.handles || null;  
		if(this.handles){  
			this.addHandleButtons(this.handles);  
		}  
		this.buttons = {  
			previous: [],  
			next: [],  
			play: [],  
			playback: [],  
			stop: []  
		};  
		if(params.addButtons){  
			for(var action in params.addButtons){  
				this.addActionButtons(action, $type(params.addButtons[action])=='array' ? params.addButtons[action] : [params.addButtons[action]]);  
			}  
		}  
		this.fx = new Fx.Tween(this.box,$extend((params.fxOptions||{duration:500,wait:false}),{property:this.modes[this.mode][0]}));  
		this.walk((params.startItem||0),true,true);  
	},  
  
	addHandleButtons: function(handles){  
		for(var i=0;i<handles.length;i++){  
			handles[i].addEvent(this.handle_event,this.walk.bind(this,[i,true]));  
		}  
	},  
  
	addActionButtons: function(action,buttons){  
		for(var i=0; i<buttons.length; i++){  
			switch(action){  
				case 'previous': buttons[i].addEvent(this.button_event,this.previous.bind(this,[true])); break;  
				case 'next': buttons[i].addEvent(this.button_event,this.next.bind(this,[true])); break;  
				case 'play': buttons[i].addEvent(this.button_event,this.play.bind(this,[this.interval,'next',false])); break;  
				case 'playback': buttons[i].addEvent(this.button_event,this.play.bind(this,[this.interval,'previous',false])); break;  
				case 'stop': buttons[i].addEvent(this.button_event,this.stop.bind(this)); break;  
			}  
			this.buttons[action].push(buttons[i]);  
		}  
	},  
  
	previous: function(manual){  
		this.walk((this.currentIndex>0 ? this.currentIndex-1 : this.items.length-1),manual);  
	},  
  
	next: function(manual){  
		this.walk((this.currentIndex<this.items.length-1 ? this.currentIndex+1 : 0),manual);  
	},  
  
	play: function(interval,direction,wait){  
		this.stop();  
		if(!wait){  
			this[direction](false);  
		}  
		this._play = this[direction].periodical(interval,this,[false]);  
	},  
  
	stop: function(){  
		$clear(this._play);  
	},  
  
	walk: function(item,manual,noFx){  
		if(item!=this.currentIndex){  
			this.currentIndex=item;  
			this.previousIndex = this.currentIndex + (this.currentIndex>0 ? -1 : this.items.length-1);  
			this.nextIndex = this.currentIndex + (this.currentIndex<this.items.length-1 ? 1 : 1-this.items.length);  
			if(manual){  
				this.stop();  
			}  
			if(noFx){  
				this.fx.cancel().set((this.size*-this.currentIndex)+'px');  
			}else{  
				this.fx.start(this.size*-this.currentIndex);  
			}  
			if(manual && this.autoPlay){  
				this.play(this.interval,'next',true);  
			}  
			if(this.onWalk){  
				this.onWalk((this.items[this.currentIndex] || null), (this.handles && this.handles[this.currentIndex] ? this.handles[this.currentIndex] : null));  
			}  
		}  
	}  
	  
});

der Aufruf erfolgt über den folgenden Code

	window.addEvent('domready',function(){  
		var sampleObjectItems = []; //NUMBER OF PICTURES IN AN ARRAY  
		  
		//FILL THE ARRAY FOR THE SLIDESHOW  
		for(var i = 1; i < numberOfPictures; i++){  
			sampleObjectItems[i] = "{title: " + i+"}";  
			}  
  
		var info6 = $('picture_box').getNext().set('opacity',0.5);  
		var nS6 = new noobSlide({  
			mode: 'vertical',  
			box: $('picture_box'),  
			items: sampleObjectItems,  
			//HEIGHT FOR THE PICTURES  
			size: 490,  
			addButtons: {  
				previous: $('prev'),  
				play: $('play'),  
				stop: $('stop'),  
				next: $('next')  
			},  
			startItem: -1,  
			button_event: 'click',  
			fxOptions: {  
				duration: 1000,  
				transition: Fx.Transitions.Back.easeOut,  
				wait: false  
			}  
		});  
		//walk to next item  
		nS6.next();  
	});

was ich erreichen möchte, ist folgendes: bei den Funktionen previous und next soll jeweils die Variable "currentIndex" ausgegeben werden. Ich habe mir zwar schon einige Sachen zur this-Funktion durchgelesen, weiß aber nicht, ob ich da schon genau hintergestiegen bin. Probiert habe ich es mit "alert(this.currentIndex);" (natürlich auch ohne "this." davor ...)

Ich weiß also nicht, wo der Fehler liegt bzw. ob das, was ich vorhabe überhaupt möglich ist.

Danke, für eure Hilfe.