Hai,
My thought is - at first Canada is a tough country to get VISA for people from Asia, Africa and other 3rd world countries. They like only people with USA,UK Visa. Then the invitation problem it was from USA. No mention about an organisation in Canada. Third the Canadian embassy is reject more visas than accepting them from all the third world countries. So Canada is a very bad choice for an international conference like Wikimania. Also Other strict VISA Rule countries like USA, UK, China, Australia etc. Seeking some friendly countries are good for better participation. My rejection reason was current economic conditions and family ties. (I submitted my marriage certificate and bank statement for that). After all we are staying in Canada for a week and WMF is sponsoring us. But they still saying the economic condition is no right.