function checkValidation(source, arguments)
{
    var ControlName = source.controltovalidate;
    var textbox = document.getElementById(ControlName);
    if (textbox.value == "")
     {
        textbox.style.backgroundColor = '#CCCCCC';
     }
     else
     {
        textbox.style.backgroundColor = '#EEEEEE';
     } 
}

function FunCheckUserName(sender, args)
{
    var strLogin=args.Value;
    if(strLogin.length<4 || strLogin.length>16)
    {
        args.IsValid = false;
        return;
    }
    args.IsValid= true;
 }