XML Header in Snippet Causing Errors

<?php
// Submit Reservation Request
############
## CONFIG ##
############
global $modx;
$Path = $modx->config['base_path'];
$ReservationRequests = $modx->db->config['dbase'].".`reservation_requests`";

//Get IP
if ($_SERVER['HTTP_X_FORWARD_FOR']) {
$ip = $_SERVER['HTTP_X_FORWARD_FOR'];
} else {
$ip = $_SERVER['REMOTE_ADDR'];
}
	
	//IF THERE'S ANY ERRORS, STOP THEM HERE, ELSE CONTINUE	
	if($_POST['vc_release'] == '' || $_POST['nights'] == '' || $_POST['adults'] == ''){
	
		echo '<h3>There were errors in your reservation request:</h3>
		<ul class="errors">';		
		if($_POST['vc_release'] == ''){
			echo '<li>Please Select a Date.</li>';
		}		
		if($_POST['nights'] == ''){
			echo '<li>Please Enter At Least One Night.</li>';
		}		
		if ($_POST['adults'] == ''){
			echo '<li>Please Enter At Least One Adult.</li>';
		}		
		echo '</ul>
		<h3>Please re-submit your request at the top of the site.</h3>';
	
	}else{ 
		######################################
		## ADDING RESERVATION REQUEST TO DB ##
		######################################
		
		if($_POST['CHECK_RESERVATION']=="TRUE"){
			//echo 'Success!';
			$Date = $_POST['vc_release'];
			$Nights = $_POST['nights'];
			$Adults = $_POST['adults'];
			$Children = $_POST['children'];
			$Insert = $modx->db->query("INSERT INTO " . $ReservationRequests . " (date_requested, nights_requested, adults, children, user_ip, user_agent) 
			VALUES ('" .$Date. "', '" .$Nights. "', '" .$Adults. "', '" .$Children. "', '" .$ip. "', '" .$_SERVER['HTTP_USER_AGENT']. "')");			
			
			/**
			 * CONVERT OUR RECENTLY INSERTED SQL DATA TO XML, SETUP THE FOLLOW PARAMETERS FOR THE FUNCTION
			 * @param mysql_resource - $queryResult - mysql query result
			 * @param string - $rootElementName - root element name
			 * @param string - $childElementName - child element name
			 */
			 
			//Set The Query Result to Simply Grab what we just inserted
			$queryResult = mysql_insert_id();
			$rootElementName = 'megaweb';
			$childElementName = 'request';
			
			function sqlToXml($result, $rootElementName, $childElementName)
			{ 
				$xmlData = "<?xml version=\"1.0\" encoding=\"ISO-8859-1\" ?>\n"; 
				$xmlData .= "<" . $rootElementName . ">";
			 
				$xmlData .= "<header sysID=\"clientsvc\" procId=\"\" password=\"\" mesgNum=\"01234\" megaSystem=\"prod\" />";
				
				while($record = mysql_fetch_object($queryResult))
				{ 
					/* Create the first child element */
					$xmlData .= "<" . $childElementName . " reqCode=\"avalReq\">";
			 
					for ($i = 0; $i < mysql_num_fields($queryResult); $i++)
					{ 
						$fieldName = mysql_field_name($queryResult, $i); 
			 
						/* The child will take the name of the table column */
						$xmlData .= "<" . $fieldName . ">";
			 
						/* We set empty columns with NULL, or you could set 
							it to '0' or a blank. */
						if(!empty($record->$fieldName))
							$xmlData .= $record->$fieldName; 
						else
							$xmlData .= "null"; 
			 
						$xmlData .= "</" . $fieldName . ">"; 
					} 
					$xmlData .= "</" . $childElementName . ">"; 
				} 
				$xmlData .= "</" . $rootElementName . ">"; 
			 
				return $xmlData; 
			}//end sqlToXml
			
			header("Location: reservation-request.html");
		
		}//end CHECK_RESERVATION']=="TRUE"
	
	}//end first if
	
?>

$blah = "<";
$blah .= "? ... ?";
$blah .= ">";