function showNewLayer(layerID)
    {
        switch(layerID)
        {
        case 1:
        {
            document.all.divLayer1.style.display="";
            document.all.divLayer2.style.display="none";
            document.all.divLayer3.style.display="none";
            document.all.divLayer4.style.display="none";
                        
            document.all.divImg1.src="images/index/a1-1.gif";
            document.all.divImg2.src="images/index/a2.gif";
            document.all.divImg3.src="images/index/a3.gif";
            document.all.divImg4.src="images/index/a4.gif";
            
        }
        break;
        case 2:
        {
            document.all.divLayer1.style.display="none";
            document.all.divLayer2.style.display="";
            document.all.divLayer3.style.display="none";
            document.all.divLayer4.style.display="none";
                      
            document.all.divImg1.src="images/index/a1.gif";
            document.all.divImg2.src="images/index/a2-1.gif";
            document.all.divImg3.src="images/index/a3.gif";
            document.all.divImg4.src="images/index/a4.gif";
            
        }
        break;
        case 3:
        {
            document.all.divLayer1.style.display="none";
            document.all.divLayer2.style.display="none";
            document.all.divLayer3.style.display="";
            document.all.divLayer4.style.display="none";

                      
            document.all.divImg1.src="images/index/a1.gif";
            document.all.divImg2.src="images/index/a2.gif";
            document.all.divImg3.src="images/index/a3-1.gif";
            document.all.divImg4.src="images/index/a4.gif";
          
        }
        break;
        case 4:
          {
            document.all.divLayer1.style.display="none";
            document.all.divLayer2.style.display="none";
            document.all.divLayer3.style.display="none";
            document.all.divLayer4.style.display="";

                      
            document.all.divImg1.src="images/index/a1.gif";
            document.all.divImg2.src="images/index/a2.gif";
            document.all.divImg3.src="images/index/a3.gif";
            document.all.divImg4.src="images/index/a4-1.gif";
          
        }
        break;

        }

        }