[Plugin: NextGEN Gallery] why doesn't my slideshow work but my gallery does?

hi,
my nextgen galleries work fine, but when i try to make a slideshow i just get a black square. not even a loading sign

https://ccgi.fforchlas.plus.com/wordpress/?p=440

here is another page i have made with gallery, but slideshow not working.

can someone please help? i have read everything i can about this, and can’t find a solution.

thank you!