Finally … Slideshare finally saw the contents of the directory when I browsed my Dropbox, and I’ve been able to upload it here http://www.slideshare.net/Mark_Childs/14-04-23-social-media-for-online-collaboration.
Apparently, according to Slideshare, I can increase my virility by adding more information (description, tags, category). I never realised it would be so easy.