Proof of actual knowledge of registration requirement is required for a conviction for failure to register. Cohens was required to register as a sex offender. He registered at an address on Alessandro Boulevard. He spent every night, kept his clothes, and received mail at his girlfriend’s apartment on Frederick Street. He was not on the lease at the Frederick address, and he did keep some things on the Alessandro address. At a trial for failure to register at the Frederick address, Cohens stipulated that he had actual knowledge of the requirement to register should he move or add a second residence, but contended that he did not reside at the Frederick address. In an appeal from his conviction for failure to register, Cohens contended that the instruction given to the jury erroneously omitted a requirement that the prosecutor prove he actually knew he was required to register at a particular address. He argued that his stipulation to having actual knowledge of his duty to register did not fill in the gap in the instructions as to knowledge. The appellate court found instructional error, but deemed it harmless beyond a reasonable doubt. Given the stipulation, no reasonable jury could have found the omitted knowledge element unproven.