The only significant issue we find users having with our J51 Slideshow is the slideshow appearing completely empty. There is a number of ways this issue can arise so we would suggest going through the following steps to ensure your slideshow is set up correctly.

1. Firstly ensure you are using the correct jQuery settings. If you are using Joomla 2.5, jQuery is not loaded by default so you will have ensure it is enabled under the jQuery tab in your slideshow settings. If you are using Joomla 3.x then jQuery is already loaded by Joomla so jQuery should be disabled in your slideshow settings.
2. For best results remove any spaces in your image filenames and ensure that the file extension is in lower case. Eg. 'my_image.jpg' NOT 'my image.JPG'.
3. Check that there is not extensions conflicting with your slideshow. Try disabling each module displayed on the same page as your slideshow until you find the conflicting module. Likewise disable each installed 3rd part plugin (Extensions -> Plugin Manager) until you find the conflicting plugin.

Note: To disable 3rd party plugins navigate to your Plugin Manager (Extensions -> Plugin Manager). Sort your plugins by ID in decending order. 3rd party (non Joomla) plugins will be listed first and will have an ID number significantly higher than your Joomla plugin which will usually be in the 400 to 500 ID range.