slideshow no longer displays (NextGEN Gallery)

I did an automatic upgrade of NextGEN Gallery, so I’m not sure which version I was at beforehand. (But I’m sure it was pretty recent.)

I had a seven-photo slideshow up at https://www.uuca.org. When I upgraded the plugin, it no longer appears.

The code I have on the page is <div class="slideshow">[slideshow=1]</div>

And the stylesheet has:

.slideshow div{
   float: right;
   border: 1px solid #ddd;
   background-color: #f3f3f3;
   padding: 4px;
   /*margin: 10px;*/
   /* optional rounded corners for browsers that support it */
   -moz-border-radius: 3px;
   -khtml-border-radius: 3px;
   -webkit-border-radius: 3px;
   border-radius: 3px;
}

The code WordPress spits out now is <div class="slideshow"></div>

Any ideas on how to get the slideshow to display again?