While you are waiting for the author’s answer, check these few things:
1) Where did you checked review of your slideshow? If you are looking at your Dashboard “Add New Post” page (where you type post), you’ll see nothing (just the code [slideshow id=1]). But if you click Preview (or Publish), you’ll see your slideshow on the open page.
2) Check whether some images are stored in the gallery that you choose for the slideshow. If the gallery that you choose is empty, you’ll see only black color in your slideshow.
3) Try to insert a slideshow into your post using the icon “Add NextGen Gallery” above the typing box. After you click on it, select from drop-down menu which gallery you want for the slideshow, and above the drop-down menu select Slideshow. Then click Insert button, and check your slide show at Preview or Published page.
Regards, and good luck.