How to select MYSQL Content with between Date

  mysql, pdo, php

how can I display values from the database of the Stand column with the help of the Datum column between two dates?

I tried the following code, but no result:

$sqlAverage10 = "SELECT Stand FROM Aktienstand WHERE Symbol=:symbol AND Datum BETWEEN :startDate AND :endDate10";
                    if ($stmtAverage10 = $pdo->prepare($sqlAverage10)) {

                            ':symbol' => $kurs['Symbol'],
                            ':startDate' => $startDate,
                            ':endDate10' => $endDate10
                        //var_dump ($stmtAverage10);
                        //echo ($startDate = $kurs['Datum']);
                        $stmtAverage10New = $stmtAverage10->fetch(PDO::FETCH_ASSOC);

:symbol = test
:startDate = 2021-10-09
:endDate = 2021-09-29

My table for e.g.:

Source: Ask PHP