向facebook(Marmalade c++）发送图片请求响应失败

经过大量的研究和几次碰壁，我几乎结束了我的代码。我可以连接到facebook，甚至发送消息请求，但我不能发送图片请求。这是代码：

            s3eFBRequest* pWallPostRequest = s3eFBRequest_WithGraphPath(MultiLoginScene::getSession(), "me/photos", "POST");
            s3eFBRequest_AddParamString(pWallPostRequest, "picture", MakeScreenshot());
            //s3eFBRequest* pWallPostRequest = s3eFBRequest_WithGraphPath(MultiLoginScene::getSession(), "me/feed", "POST");
            //s3eFBRequest_AddParamString(pWallPostRequest, "message", "Here's a wall post!");
            s3eFBRequest_AddParamString(pWallPostRequest, "access_token", s3eFBSession_AccessToken(MultiLoginScene::getSession()));
            s3eFBRequest_Send(pWallPostRequest, GraphRequestCallback, NULL);

关于MakeScreenshot（）

static void flipVertical(unsigned char *data, int w, int h)
{
  int x, y, i1, i2;
  unsigned char temp;
  for (x=0;x<w;x++){
    for (y=0;y<h/2;y++){
      i1 = (y*w + x)*3; // this pixel
      i2 = ((h - y - 1)*w + x)*3; // its opposite (across x-axis)
      // swap pixels
      temp = data[i1];
      data[i1] = data[i2];
      data[i2] = temp;
      i1++; i2++;
      temp = data[i1];
      data[i1] = data[i2];
      data[i2] = temp;
      i1++; i2++;
      temp = data[i1];
      data[i1] = data[i2];
      data[i2] = temp;
    }
  }
}
const char* MainMenuScene::MakeScreenshot()
{
  static int count = 0;
  static char file[] = "PicaSim-00000.png";
  sprintf(file, "PicaSim-%05d.png", count++);
 // int w = s3eSurfaceGetInt(S3E_SURFACE_WIDTH);
  //int h = s3eSurfaceGetInt(S3E_SURFACE_HEIGHT);
  int w = 600;
  int h = 600;
  int dataSize = w * h * 3;
  unsigned char *framebuffer = 
    (unsigned char *) malloc(dataSize * sizeof(unsigned char));
  glReadPixels(0, 0, w, h, GL_RGB, GL_UNSIGNED_BYTE, framebuffer);
  flipVertical(framebuffer, w, h);
  /* CIwImage image;
  image.SetFormat(CIwImage::BGR_888);
  image.SetWidth(w);
  image.SetHeight(h);
  image.SetBuffers(framebuffer, dataSize);
  image.SavePng(file);
  free(framebuffer);*/
  return (const char *)framebuffer;
}

毕竟，我从回拨中收到了一个失败的响应。。。我做错了什么？我只需要发送一张截图到脸书。。。知道为什么不工作吗？

编辑：

所以我试着发送一个URL作为参数，但仍然不起作用

s3eFBRequest* pWallPostRequest = s3eFBRequest_WithGraphPath(MultiLoginScene::getSession(), "me/photos", "POST");
            s3eFBRequest_AddParamString(pWallPostRequest, "picture", "http://img1.wikia.nocookie.net/__cb20130407100142/onepiece/pt/images/d/d8/Goku_2.jpg");
            s3eFBRequest_AddParamString(pWallPostRequest, "access_token", s3eFBSession_AccessToken(MultiLoginScene::getSession()));
            s3eFBRequest_Send(pWallPostRequest, GraphRequestCallback, NULL);

但仍然不起作用。。。有线索吗？