Upload Image Issue In Server

if (isset($_POST['add_chk_doc'])) {

    $filecontent = $_FILES['chk_doc_image']['name'];
    $dividefile = explode(".", $filecontent);
    $totaldivdedcontent = (sizeof($dividefile) - 1);
    $extension = $dividefile[$totaldivdedcontent];
    if ($extension != 'jpg' && $extension != 'jpeg' && $extension != 'png') {

        $flash->setMessage(array(
            "type" => "danger",
            "message" => "Imported file in Invalid. Please check if the uploaded file is Image."
        ));
        $common->redirect_to_page(BASE_PATH . 'check_document.php');

    }
    else {

        $uniqid = date("YmdHis");
        $newfilename = $uniqid . "_chk_doc." . $extension;
        $upload_path = BASE_PATH."upload/" . $newfilename;
        $move = move_uploaded_file($_FILES['chk_doc_image']['tmp_name'], $upload_path);

    }
    $ca_code = 'LAN-CDOC' . '-' . rand(0, 9999);
    $doc_check = implode(",",$_POST["chk_status"]);

    $parameter = array(
        "chk_doc_code" => $ca_code,
        "batch_code" => $_POST['batch_no'],
        "student_code" => $_POST['student_no'],
        "doc_name" =>$_POST['doc_name'],
        "chk_status"=>$doc_check,
        "chk_by" =>$_POST['chk_by'],
        "status" => $_POST['status'],
        "chk_doc_image" =>$newfilename
    );

    $result = $check_document->checkDocumentAdd($parameter);
    if ($result) {
        $flash->setMessage(array(
            "type" => "success",
            "message" => "Check Document Successfully Completed"
        ));
    } else {
        $flash->setMessage(array(
            "type" => "danger",
            "message" => "Check Document Failed!!!"
        ));