We established that the employer was never served with the notice of assignment of the claim petition to a judge. While the claimant’s attorney had properly served the claim petition itself on the employer, we correctly argued that it is the notice of assignment that triggers the employer’s obligation to file an answer within 20 days. We were able to prove that the employer’s address on the notice of assignment had the wrong zip code and that the employer was never served. Therefore, the judge found that the employer had a reasonable excuse for its late answer to the claim petition.