37 CFR §228.1

1. (a)Failure to serve a respondent who is not a necessary party. If a claimant fails to timely complete service on a respondent who is not a necessary party, pursuant to § 222.14 of this subchapter, the Copyright Claims Board (Board) shall dismiss that respondent from the proceeding without prejudice. The proceeding shall continue against any remaining respondents.
2. (b)Failure to serve a respondent who is a necessary party. If a claimant fails to timely complete service on a respondent who is a necessary party, pursuant to § 222.14 of this subchapter, the Board shall dismiss the proceeding without prejudice.
3. (c)Complete failure to serve respondents. For a claim to proceed, a claimant must complete service on at least one respondent. If a claimant does not timely file any proof of service, the Board shall dismiss the proceeding without prejudice.