ไม่สามารถกรอกข้อมูลเข้าในหลายตารางและก็ส่งเมลล์ยืนยันไม่ได้

$strSQL = "SELECT * FROM user_all WHERE Username = '".trim($_POST['username'])."' ";
	$objQuery = mysql_query($strSQL);
	$objResult = mysql_fetch_array($objQuery);
	if($objResult)
	{
			echo "Username already exists!";
	}
	else
	{	




		$Uid = mysql_insert_id();
		echo "Register Completed!<br>Please check your email to activate account";		

		$strTo = $_POST["email"];
		$strSubject = "Activate Member Account";
		$strHeader = "Content-type: text/html; charset=windows-874\n"; // or UTF-8 //
		$strHeader .= "From: [email protected]\nReply-To: [email protected]";
		$strMessage = "";
		$strMessage .= "Welcome : ".$_POST["firstname"]."".$_POST["lastname"]."<br>";
		$strMessage .= "=================================<br>";
		$strMessage .= "Activate account click here.<br>";
		$strMessage .= "http://wdcoop.wdthjobs.com/activate.php?sid=".session_id()."&uid=".$Uid."<br>";
		$strMessage .= "=================================<br>";
		$strMessage .= "Western Digital<br>";

		$flgSend = mail($strTo,$strSubject,$strMessage,$strHeader); 
	
	}
	echo"<a href=\"login.php\">Click to Login!!</a>";

	mysql_close();
?>