รบกวนช่วยตรวจสอบ code upload file ให้หน่อยค่ะว่าผิดตรงไหน

<form name="formname" method="POST" action="upload.php">
    <table id="tblatt" border="0" border-color="#000" width="100%" height="50">
        <tr>
            <td>
                <div class="loginform_row">
                    <label>Attach File:</label>
                    <input type="file"  class="loginform_input" id="filUpload" name="filUpload" />
                    <input type="submit" class="loginform_submit" value="Upload" name="submit"/>
                </div>
            </td>
        </tr>
    </table>
</form>

if(isset($_POST['submit'])) {
    $tmp_file = $_FILES['filUpload']['tmp_name'];
    $target_file = basename($_FILES['filUpload']['name']);
    $upload_dir = "upload";

    if(move_uploaded_file($tmp_file, $upload_dir."/".$target_file)) {
       echo "File uploaded successfully.";
     } else {
       echo "File uploaded Failed.";
     }
}