The Canadian helicopter company that was scheduled to begin stringing the cable from the Canadian side to Goat Island on the U.S. side informed Wallenda they had Transport Canada's permission to do the work, but didn't have a permit from the Federal Aviation Authority.
FAA approval could take weeks and the set-up was to begin next Tuesday, the Toronto Star said.
Wallenda is scheduled to make the walk June 15.
The plan was for Niagara Helicopters to take a rope from the Canadian side to Goat Island. Then, the thick steel cable Wallenda would walk on would be attached to the rope, which would be winched across.
The veteran daredevil has an ally in ABC television, which plans to broadcast the walk live.
Network spokesman Jeffrey Schneider told the Star ABC also needs a separate cable strung to carry cameras.
"We are completely confident that there will be a wire across the falls for this walk," he said. "We're in touch with another helicopter company that does rigging and construction and they're already certified for all this kind of work, so we're not particularly concerned."