mysqli_stmt::bind_param error message

[Erwin007]

Instead of the $from = $_GET['from'] ?? ''; I have this:
 

<?php
		$from = "2023-06-15";  //$_GET['from'] ?? '';
		$to = $_GET['to'] ?? '';
		$tdata = "";
		
	if (!empty($from) && !empty($to)) {
		$query = "
		SELECT products.product_name, sum(inventory.inventory_amount) as amount
		FROM `inventory`
		JOIN products on products.product_id = inventory.inventory_productid
		WHERE inventory.inventory_date BETWEEN '$from' AND '$to'
		GROUP BY products.product_name";
		
		$result = mysqli_prepare($con,$query);
		$result->bind_param('ss', $from, $to);
		$result->execute();
		$result->bind_result($product_name, $amount);

The result is correct but I have an error-message:
PHP Warning:  mysqli_stmt::bind_param(): Number of variables doesn't match number of parameters in prepared statement in /home/xxxxxx/public_html/ticketapp/inv_rep.php on line 88
Line 88: $result->bind_param('ss', $from, $to);

The problem is obviously the $from = "2023-06-15" instead of $_GET['from'] ?? ''; but how to solve this?
Thanks.

[Barand]

You are executing a query passing two bound parameter values, but your query has no placeholders for those parameters.

[Erwin007]

Instead of WHERE inventory.inventory_date BETWEEN '$from' AND '$to' I did: WHERE inventory.inventory_date BETWEEN ? AND ? and that works correct.
Thanks