Why can't Constant get a visa to attend the show? 

"There are some people who think we are in the business of selling the image of the lwa (spirits)," Constant says in a film that accompanies the Fowler Museum show. "But we don't sell their image. We work with them, because the spirits are always with us. We don't see them but they are all around us. All over the world."

WORLD
What's driving the crisis in Haiti
As Constant's art is gaining international recognition, Haiti is sinking deeper into political instability and violence. There are no elected leaders in Haiti's parliament. Schools and hospitals are closing, and the national police are outgunned by gangs which control much of the capital, Port-au-Prince. Hunger is widespread throughout the country.

In fact, Constant was unable to get a visa to attend the opening of her show due to this instability. Still, Constant is dedicated to depicting Haiti as more than a country in despair, as in her piece about the catastrophic 2010 earthquake.
Constant cannot get a visa to attend her show opening because of the instability and violence occurring in Haiti.