php adodb error type mismatch on parameterized query
if (isset($_POST['submit'])){
    $username = $_POST['username'];
    $password = $_POST['password'];
    $query = "select user_id from users where user_id = '?' and PWD = '?'";
    $params = array($username, $password);
    $execute = $conn->Execute($query,$params) or die("Error in query: $query. " . $conn->ErrorMsg());
    if ($execute->EOF){
         echo 'fail';
    }
    else {
         echo 'yay';
    }
}

$conn = new COM ("ADODB.Connection") or die("Cannot start ADO");
$connStr = "PROVIDER=SQLOLEDB;SERVER=".$server.";UID=".$myUser.";PWD=".$myPass."; DATABASE=".$myDB;
$conn->open($connStr); //Open the connection to the database

Fatal error: Uncaught exception 'com_exception' with message 'Source: Provider Description: Type mismatch.' in C:CGI ScriptsSITESSkillSTICK_2011login.php:22 Stack trace: #0 C:CGI ScriptsSITESSkillSTICK_2011login.php(22): com->Execute('select user_id ...', Object(variant)) #1 {main} thrown in C:CGI ScriptsSITESSkillSTICK_2011login.php on line 22