Undefined Index for Sales Image

<?php
include 'include/AnonymousHeader.php';

$CON = @mysqli_connect('localhost', 'root', '', 'allyouneed') OR die('Could not connect to MySQL: ' . mysqli_connect_error());

    ?>

    <table width="700">
        <tr>
            <td>
                <h1>Sales Registration</h1>
            </td>
        </tr>


        <?php
        if (!(empty($_SESSION['LoginStatus']))) {
        $SQL1 = "SELECT *
                     FROM sales";
        $STM1 = @mysqli_query($CON, $SQL1);

        $ROW = 0;
        $SalesID = "";

        if ($STM1) {
            $ROW = @mysqli_num_rows($STM1);
        } else {
            echo mysqli_error($CON);
        }

        if ($ROW == 0) {
            $SalesID = "SALES00001";
        } else {
            $SalesID = sprintf("SALES%05d", $ROW + 1);
        }

        if (isset($_POST['SUBMIT'])) {
            $SalesProdName = $_POST['SalesProdName'];
            $SalesDescription = $_POST['SalesDescription'];
            $SalesImage = $_FILES['SalesImage'];
            $SalesQty = $_POST['SalesQty'];
            $SalesPrice = $_POST['SalesPrice'];
            $SalesCategory = $_POST['SalesCategory'];
            $MID = $_SESSION['IDInfo'];

            $error = array();


            if (!empty($SalesProdName)) {
                if (!(preg_match('/^[A-Za-z0-9]+$/', $SalesProdName))) {
                    $error[] = 'Sales Name must only contains charater(s) or digit(s)';
                }
            } else {
                $error[] = 'Sales Name must not be empty.';
            }

            if (empty($SalesDescription)) {
                $error[] = 'Sales Description must not be empty.';
            }

            if ($SalesImage['size'] == 0) {
                $error[] = 'No image was selected';
            } else if ($SalesImage['error'] > 0) {
                switch ($SalesImage['error']) {
                    case UPLOAD_ERR_NO_FILE:
                        $error[] = 'The file is not exist.';
                        break;
                    case UPLOAD_ERR_FORM_SIZE:
                        $error[] = 'image uploaded is too large. Maximum 1MB allowed.';
                        break;
                    default:
                        $error[] = 'There was an error while uploading the image.';
                        break;
                }
            } else if ($SalesImage['size'] > 1048576) {
                $error[] = 'image uploaded is too large. Maximum 1MB allowed.';
            } else {
                $ext = strtolower(pathinfo($SalesImage['name'], PATHINFO_EXTENSION));
                if ($ext != 'jpg' && $ext != 'jpeg' && $ext != 'gif' && $ext != 'png') {
                    $error[] = 'Only JPG, GIF and PNG format are allowed.';
                }
            }

            if (!empty($error)) {
                ?>
                <table border="1" bordercolor="red" bgcolor="pink" width="700">
                    <tr>
                        <td>
                            <h3>There are error(s) occured at the following area:</h3>
                            <?php
                            foreach ($error as $ERR) {
                                ?>
                                <font color="red">=> <?php printf("%s", $ERR); ?></font><br/>
                                <?php
                            }
                            ?>
                        </td>
                    </tr>
                </table>                    
                <?php
            } else {

                $save_as = $SalesID . '.' . $ext;
                move_uploaded_file($SalesImage['tmp_name'], 'image/' . $save_as);
                $SalesImage = 'image/' . $save_as;
                $SalesStatus = "Available";
                date_default_timezone_set("Asia/Kuala_Lumpur");
                $CurrentDate = date('Ymd');
                $CurrentDate = substr($CurrentDate, 0, 4) . '-' . substr($CurrentDate, 4, 2) . '-' . substr($CurrentDate, 6, 2);
                $SQLSAL2 = "INSERT INTO sales
                   (SalesID, SalesProdName, SalesCategory, SalesImage, SalesDescription, SalesQty, SalesPrice, SalesStatus, MID, SalesDate)
                    VALUES('$SalesID', '$SalesProdName', '$SalesCategory', '$SalesImage' , '$SalesDescription', '$SalesQty', '$SalesPrice', '$SalesStatus', '$MID', '$CurrentDate')";
                $SAL2 = @mysqli_query($CON, $SQLSAL2);
                if ($SAL2) {
                    ?>
                    <script language="javascript">alert("Sales Registered.")</script>
                    <?php
                } else {
                    echo mysqli_error($CON);
                }
            }
        }
    }
    ?>    


    <form action="" method="POST" ENCTYPE = "multipart/form-data">
        <table>

            <tr>
                <td>
                    Sales ID: 
                </td>
                <td>
                    <?php echo "$SalesID"; ?>
                </td>                
            </tr>

            <tr>
                <td>
                    Product Name :
                </td>
                <td>
                    <input type="text" name="SalesProdName" id="SalesProdName" maxlength="50"/>
                </td>
            </tr>

            <tr>
                <td>
                    Category :
                </td>
                <td>
                    <select name="SalesCategory" id="SalesCategory">
                        <option>Select one</option>
                        <option>Art</option>
                        <option>Book</option>
                        <option>Digital Device</option>
                        <option>Electronic</option>
                        <option>Entertainment</option>
                        <option>Model Figure</option>
                        <option>Sports</option>
                        <option>Vehicles</option>
                        <option>Video Games</option>
                        <option>Others</option>
                    </select>
                </td>
            </tr>
            <tr>
                <td>
                    Product Image :
                </td>
                <td>
                    <input type="hidden" name="MAX_FILE_SIZE" value="1048576" />
                    <input type="file" name="SalesImage" id="SalesImage"/>
                </td>
            </tr>

            <tr>
                <td>
                    Product Description :
                </td>
                <td>
                    <textarea rows="3" cols="50" name="SalesDescription" id="SalesDescription"></textarea>
                </td>
            </tr>

            <tr>
                <td>
                    Quantity : 
                </td>
                <td>
                    <input type="text" name="SalesQty" id="SalesQty">
                </td>
            </tr>

            <tr>
                <td>
                    Product Price :
                </td>
                <td>
                    <input type="text" name="SalesPrice" id="SalesPrice"/>
                </td>
            </tr>


            <tr>
                <td align="center" colspan="2">
                    <input type="submit" value="Submit" name="SUBMIT" ID="SUBMIT" />
                    <input type="reset" value="Reset" />
                </td>
            </tr>
        </table>
    </form>   


    <?php
    include 'include/footer.php'
    ?>