最后一张跳转到第一张是成功的但，为什么最后一张图片显示不了，出现空白页。

function pic_play(offset){
			var newLeft=parseInt(picPlay_11.style.left) + offset;
		
			picPlay_11.style.left=newLeft+'px';
				if(newLeft > -900){
					picPlay_11.style.left = -5400 + 'px';
				}
				if(newLeft < -5400){
					picPlay_11.style.left = -900 + 'px';
				}
		}
		next.onclick=function(){
			pic_play(-900);
		}
		prev.onclick=function(){
			pic_play(900);
		}


 <div id="picPlay_11" class="picPlay_1" style="left:-900px;">
	 	<img src="images/play/6.png"alt="6"/>
	  	<img src="images/play/1.png"alt="1"/>
	  	<img src="images/play/2.png"alt="2"/>
		<img src="images/play/3.png"alt="3"/>
		<img src="images/play/4.png"alt="4"/>
		<img src="images/play/5.png"alt="5"/>
		<img src="images/play/6.png"alt="6"/>
		<img src="images/play/1.png"alt="1"/>
		
	  </div>