ช่วยด้วยคับ syntax error, unexpected '"', expecting T_STRING or T_VARIABLE or T_NUM_STRING in หาไม่เจอ

<?php
if(isset($_POST["send"]))
	process_form();
else if(isset($_POST["send2"]))
	process_form2();
else
	show_form();



function show_form() {
	echo <<<HTMLBLOCK
	<h3>รหัสสินค้า</h3>
	<form method="POST"  action="{$_SERVER['PHP_SELF']}">
	ID: <input type="text" name="proid" size="5" maxlength="5"><br><br>
	<input type="submit" name="send" value="ยืนยัน">
	</form>
HTMLBLOCK;
}

function process_form() {
	$pcode = trim($_POST["proid"]);       <<< Line 22
	
	$cn = mysqli_connect("localhost", "root", "1234");
	
	if(!$cn){
		echo "Cannot connect to MySQL Server<br>";
		exit;
	}

	mysqli_select_db($cn, "base");
	$ch = "SELECT * FROM product WHERE ProductID={$pcode}";
	$op = mysqli_query($cn,$ch) or die("error $ch");

	$rows = mysqli_fetch_array($op);

	echo <<<HTMLBLOCK
	<h3>แก้ไขข้อมูลสินค้า</h3>
	<form method="POST" action="{$_SERVER['PHP_SELF']}" >
	Product_Type: <input type="text" name="uptype" size="20" value="{$rows['ProductType']}"><br>
	Product_Name: <input type="text" name="upname" size="20" value="{$rows['ProductName']}"><br>
	Price: <input type="text" name="upprice" size="10" value="{$rows['SellPrice']}"><br>
	Stock: <input type="text" name="upstock" size="5" value="{$rows['Num_inStock']}"><br>
	<input type="submit" name="send2" value="ยืนยัน">
	</form>
HTMLBLOCK;
	mysqli_close($cn);
}

function process_form2() {

	$uptype = trim($_POST["uptype"]);
	$upname = trim($_POST["upname"]);
	$upprice = trim($_POST["upprice"]);
	$upstock = trim($_POST["upstock"]);
	
	if(($uptype == "") or ($upname == "") or ($upprice == "") or ($upstock == "")){
		echo "<font color=\"red\">Error : คุณป้อนข้อมูลไม่ครบ</font><br>";
		process_form();
		exit;
	}

	
	$uptype = addslashes($uptype);
	$upname = addslashes($upname);
	$upprice = doubleval($upprice);
	$upstock = addslashes($upstock);

	$cn = mysqli_connect("localhost", "root", "1234");
	
	if(!$cn){
		echo "Cannot connect to MySQL Server<br>";
		exit;
	}

	mysqli_select_db($cn, "base");
	$sql = "UPDATE product SET ProductType={$uptype}, ProductName={$upname}, SellPrice={$upprice}, Num_inStock={$upstock} WHERE ProductID={$pcode}";
	$result = mysqli_query($cn, $sql);
	
	if($result){
		$row = mysql_fetch_array($result);
		echo "<h3>ผลการแก้ไขข้อมูลสมาชิก</h3>\n";
		echo "หมายเลขสินค้า ".$row['ProductID']."<br>";
		echo "ประเภท ".$row['ProductType']."<br>";
		echo "ชื่อ ".$row['ProductName']."<br>";
		echo "ราคา ".$row['SellPrice']."<br>";
		echo "จำนวน ".$row['Num_inStock']."<br>";
		
	}
	else{
		echo "เกิดข้อผิดพลาดในการแก้ไขข้อมูล<br>";
	}
	mysqli_close($cn);
		
	}
}
?>