function SetActive(tab)
    {
        if(tab == 'Tab1')
        {
            
            document.all("Tab1").background = "/images/tab_01_select.gif";
            document.all("Tab2").background = "/images/tab_01.gif";
            document.all("Tab3").background = "/images/tab_01.gif";
            document.all("Layer1").style.visibility = "visible";
            document.all("Layer1").style.display = "block";
            document.all("Layer2").style.visibility = "hidden";
            document.all("Layer2").style.display = "none";
            document.all("Layer3").style.visibility = "hidden";
            document.all("Layer3").style.display = "none";
        }
        else if(tab == 'Tab2')
        {
            document.all("Tab1").background = "/images/tab_01.gif";
            document.all("Tab2").background = "/images/tab_01_select.gif";
            document.all("Tab3").background = "/images/tab_01.gif";
            document.all("Layer1").style.visibility = "hidden";
            document.all("Layer1").style.display = "none";
            document.all("Layer2").style.visibility = "visible";
            document.all("Layer2").style.display = "block";
            document.all("Layer3").style.visibility = "hidden";
            document.all("Layer3").style.display = "none";
        }
         else if(tab == 'Tab3')
        {
            document.all("Tab1").background = "/images/tab_01.gif";
            document.all("Tab2").background = "/images/tab_01.gif";
            document.all("Tab3").background = "/images/tab_01_select.gif";
            document.all("Layer1").style.visibility = "hidden";
            document.all("Layer1").style.display = "none";
            document.all("Layer2").style.visibility = "hidden";
            document.all("Layer2").style.display = "none";
            document.all("Layer3").style.visibility = "visible";
            document.all("Layer3").style.display = "block";
            
        }
        
    }