Why did opposition candidates boycott the 1991 presidential election in Burkina Faso?

Opposition candidates boycotted the 1991 presidential election in Burkina Faso because they were protesting the refusal of Blaise Compaoré to hold a national conference on political reform.1

Following the promulgation of a new constitution earlier that year, Compaoré resigned from the military to run for president as a civilian. Due to the boycott, he ran unopposed and was elected to a seven-year term.1