ปัญหาเช็ตอีเมลล์คะ ในภาพนี้เออเรอร์ในกรณีที่กรอกรูปแบบอีเมลล์ถูกต้อง แล้ว user ที่สมัคร

<?php
<form method="post" action="check_regis.php" name="myForm" onSubmit="JavaScript:return fncSubmit();">
<input name="email" type="text" id="email" /> 
 <input type="submit" name="submit" value="Submit" />
<input type="reset" name="reset" value="Clear" />
</form> 

?>

<?php
function checkemail($checkemail) {
	if(ereg( "^[^@ ]+@([a-zA-Z0-9\-]+\.)+([a-zA-Z0-9\-]) {2}|net|com|gov|mil|org|edu|int)$",$checkemail) ){

	return true;
	} else { 
	return false;
	}
}
?>

<?php
<?
$username = $_POST["username"];
$password = $_POST["password"];
$password2 = $_POST["password2"];
$firstname =  $_POST["firstname"];
$lastname =  $_POST["lastname"];
$company =  $_POST["company"];
$gender = $_POST["gender"];
$day = $_POST["day"];
$month = $_POST["month"];
$year = $_POST["year"];
$email = $_POST["email"];
$address = $_POST["address"];
$country = $_POST["country"];
$postal_code = $_POST["postal_code"];
$tel = $_POST["tel"];
$fax = $_POST["fax"];
$mobile = $_POST["mobile"];
$favourite_color = $_POST["favourite_color"];
include('function.php');

if(!checkemail($email)){
echo "<script language='javascript'>alert('Invalid Email format.');history.back();</script> ";

}


$sql_user = "Select * From tbregister Where username='$username' ";
$result = mysql_query($sql_user);
$row= mysql_fetch_array($result);
if ($row['username'])
echo "<script language='javascript'>alert('This username is already in use.');history.back();</script> ";
include "connectdb.php";

$sql = <<<SQL
		insert into tbregister values('','$username','$password','$password2','$firstname','$lastname','$company','$gender','$day','$month','$year','$email','$address','$country',$postal_code,$tel,$fax,$mobile,'$favourite_color');
SQL;
  

	$result=mysql_query($sql);
		
		$msg = "";
		$resetForm = "";
		if($link==0){
			$msg = "<p class='red2'>";
			$msg .= "Sorry, you are not able to be registered."; 
			echo "<meta http-equiv='refresh' content='5; url=re_cus.php' />";
		
		}
		else{
			echo "<p class='red2'>Thank you. You are already registered.</p>";
		    echo "<meta http-equiv='refresh' content='5; url=service.php' />";
			$resetForm = "document.getElementById('myForm').reset();";
		
		}

		mysql_close($link);
?>