Simplify the following text for a Grade 7 native English-speaking person.
Original: Warne 's New York office `` failed to register the copyright for The Tale of Peter Rabbit in the United States '' and unlicensed copies of the book '' ( from which Potter would receive no royalties ) began to appear in the spring of 1903 .
Simplified: Warne 's New York office did not register the copyright for The Tale of Peter Rabbit in the United States . Because of this , unlicensed copies of the book began to appear in the spring of 1903 .