Fatal error: Call to a member function rowCount() on boolean in C:MAMPhtdocssamplespdoconexao.php on line 12

<?php
    try {
        $pdo = new PDO("mysql:host=localhost;dname=dashboard","root","root");
    } catch(PDOException $e) {
        echo '<b style="color:red">'.$e->getMessage().'</b>';
    }

    $buscarUsuario = $pdo->query("SELECT * FROM usuarios");

    $buscarUsuario->rowCount(); //linha 12