[Plugin: WOW Slider] Add New: Won't upload .zip file

When I try to upload my zipped Wow Slider file, I get an error message that says “Wrong Slider.” No other explanation. I’ve tried uploading the file from a different computer, I’ve tried uploading it via FTP… Nothing is working. Please help!

http://wordpress.org/extend/plugins/wow-slider-wordpress-image-slider-plugin/