Help with 2 Jquery sliders on one page

Hi, I have a page where I want to use two jquery sliders. To be honest my javascript knowledge is pretty awful, but I've managed to set up the sliders. The only problem is that when I press the next button on one of the sliders, it triggers the wrong one to move.

I've tried using separate id's and having a different javascript file for each slider (have no idea if this is the right thing to do )

If anyone knows how to fix this I would really appreciate any help.

The code i am using for the sliders is:

(function($) {

$.fn.easySlider = function(options){

	// default configuration properties
	var defaults = {
		prevId: 		'prevBtn',
		prevText: 		'Previous',
		nextId: 		'nextBtn',	
		nextText: 		'Next',
		orientation:	'', //  'vertical' is optional;
		speed: 			800			
	}; 

	var options = $.extend(defaults, options);  

	return this.each(function() {  
		obj = $(this); 				
		var s = $("li", obj).length;
		var w = obj.width(); 
		var h = obj.height(); 
		var ts = s-1;
		var t = 0;
		var vertical = (options.orientation == 'vertical');
		$("ul", obj).css('width',s*w);			
		if(!vertical) $("li", obj).css('float','left');
		$(obj).after('<span id="'+ options.prevId +'"><a href=\"javascript:void(0);\">'+ options.prevText +'</a></span> <span id="'+ options.nextId +'"><a href=\"javascript:void(0);\">'+ options.nextText +'</a></span>');		
		$("a","#"+options.prevId).hide();
		$("a","#"+options.nextId).hide();
		$("a","#"+options.nextId).click(function(){		
			animate("next");
			if (t>=ts) $(this).fadeOut();
			$("a","#"+options.prevId).fadeIn();
		});
		$("a","#"+options.prevId).click(function(){		
			animate("prev");
			if (t<=0) $(this).fadeOut();
			$("a","#"+options.nextId).fadeIn();
		});	
		function animate(dir){
			if(dir == "next"){
				t = (t>=ts) ? ts : t+1;	
			} else {
				t = (t<=0) ? 0 : t-1;
			};								
			if(!vertical) {
				p = (t*w*-1);
				$("ul",obj).animate(
					{ marginLeft: p }, 
					options.speed
				);				
			} else {
				p = (t*h*-1);
				$("ul",obj).animate(
					{ marginTop: p }, 
					options.speed
				);					
			}
		};
		if(s>1) $("a","#"+options.nextId).fadeIn();	
	});

};

})(jQuery);