Validate email address ทำงานไม่ถูกต้อง return false;

function validateForm() {
		var x1 = document.reg.fullname.value;
		var x2 = document.reg.lastname.value;
		var x3 = document.reg.uname.value;
		var x4 = document.reg.uemail.value;
		var Email=/^([a-zA-Z0-9\_\-\.])+@([a-zA-Z0-9])+\.([a-zA-Z0-9]{2,6})$/;

		   if (x1.length == "") {
		   	 alert("Please enter name!") ;
		   } else if (x2.length == "") {
			   alert("Please enter lastname!") ;
		   } else if (x3.length == "") {
			   alert("Please enter username!") ;
		   } else if (x4.length == "") {
			   alert("Please enter email address!");

                   } else if (x4.length != Email) {
				 alert ("Please enter correct email address!");
				 return false;
	          }
 }