A yearly University of Southern California summit that focuses on economic development on the African continent is missing a significant component this year: Africans.

The African Global Economic and Development Summit, which invites representatives from all over the continent to discuss issues of environment, economy, health and other topics on a world stage, had opened its doors to government officials and speakers from Sierra Leone, Ghana, Ethiopia, Nigeria, South Africa, and Guinea. But because of a denial of travel visas, none of the delegates were allowed into the United States.

“Usually we get 40 percent that get rejected but the others come,” Mary Flowers, chair of the summit told Voice of America. This year it was 100 percent. Every delegation. And it was sad to see, because these people were so disheartened.”

About 100 attendees were unable to obtain visas from the U.S. State Department, she says. It is unclear why the visas had been denied, but Flowers said the individuals who were rejected had been called for embassy interviews just days before they were set to depart, although the had applied far ahead of time.

“I have to say that most of us feel it’s a discrimination issue with the African nations,” said Flowers. “We experience it over and over and over, and the people being rejected are legitimate business people with ties to the continent.”

U.S. Embassies in various countries may deny non-immigrant visas for a variety of reasons and without warning. But so far there has been no explanation of why all of the visas from each of the counties with delegates planning travel to the summit were denied. None of them are on the list named in President Trump’s travel ban executive order.

But this is not the only disappointment recently issued by a U.S. Embassy in Africa. Nkabom Children’s Cultural Troupe, a group of youths from Okurase, Ghana were refused entry to the United States earlier this month although they had planned performances around the Charleston, S.C., area, and also in New York, according to the Charleston Post and Courier.