XNA Проблема с отрисовкой части 2D-спрайта на экране, в результате появляются черные линии

В настоящее время я пытаюсь отобразить лист 2D-спрайтов, используя приведенный ниже код, и все, что в результате получается, это рендеринг только цвета фона изображения с черными линиями, проходящими через него. Изображение сохраняется как файл .png с помощью gimp.

Я протестировал случайные листы спрайтов, скачанные из сети, и они отлично отрисовываются. Есть ли способ, которым я мог бы неправильно сохранить файл png?

Размер кадра должен быть 27 x 27, что соответствует высоте фактического файла изображения, за которым следует желаемая ширина кадра.

Вот лист, который я сейчас использую:

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;


namespace WindowsGame3
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;

        //Texture2D holds the image
        Texture2D character;

        //Holds position of character on screen
        Vector2 Position = new Vector2(200, 200);

        //Frames current size (W, H)
        Point frameSize = new Point(27, 27);

        //Which frame we are currently on
        Point currentFrame = new Point(0, 1);

        //How many frames on a line, followed by how many lines
        Point sheetSize = new Point(13, 1);

        //Sprite animation speed
        float speed = 15;

        //
        KeyboardState currentState;
        KeyboardState theKeyboardState;
        KeyboardState oldKeyboardState;

        enum State
        {

            Walking,
            Punch,
            Jump,
            JumpForward,
            JumpBackgwards


        }

        //First state we have when character is walking
        State mCurrentState = State.Walking;

        //Adjusts frames draw speed
        TimeSpan nextFrameInterval = TimeSpan.FromSeconds((float)1 / 16);

        //Changes each time we need to go to the next frame
        TimeSpan nextFrame;

        public Game1()
        {
            //Adjusts how fast things happen in XNA
            TargetElapsedTime = new TimeSpan(0, 0, 0, 0, 100);

            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";
        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
            // TODO: Add your initialization logic here

            base.Initialize();
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            // Create a new SpriteBatch, which can be used to draw textures.
            spriteBatch = new SpriteBatch(GraphicsDevice);

            // TODO: use this.Content to load your game content here

            //Sprite sheet we are using
            character = Content.Load<Texture2D>("MainSprite");


        }

        /// <summary>
        /// UnloadContent will be called once per game and is the place to unload
        /// all content.
        /// </summary>
        protected override void UnloadContent()
        {
            // TODO: Unload any non ContentManager content here
        }

        /// <summary>
        /// Allows the game to run logic such as updating the world,
        /// checking for collisions, gathering input, and playing audio.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Update(GameTime gameTime)
        {
            // Allows the game to exit
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
                this.Exit();

            // TODO: Add your update logic here

            base.Update(gameTime);
        }

        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);

            // TODO: Add your drawing code here


            spriteBatch.Begin();

            //Gives the name of the Texture2D variable, then the position.
            //By creating a rectangle, only what is inside will be drawn on the screen.
            spriteBatch.Draw(character, Position, new Rectangle(
                                frameSize.X * currentFrame.X,
                                frameSize.Y * currentFrame.Y,
                                frameSize.X,
                                frameSize.Y),
                                Color.White, 0, Vector2.Zero, 1, SpriteEffects.None, 0);

            //frameSize.X * currentFrame.X gives current position of frame on X. Same with Y.
            //frameSize.X, frameSize.Y is the width and height of the current frame.

            spriteBatch.End();

            base.Draw(gameTime);
        }
    }
}