shall again be notified that the counterclaim is deficient, and the counterclaimant shall be provided a second opportunity to amend the counterclaim within 30 days after the date of the second notice. If the counterclaim is refiled and served again within that second 30-day period and is compliant, the counterclaimant and such other parties shall be so notified, but if the counterclaim still fails to comply, upon confirmation of such noncompliance by a Copyright Claims Officer, the counterclaim, but not the proceeding, shall be dismissed without prejudice. (3) Dismissal of unsuitability The Copyright Claims Board shall dismiss a claim or counterclaim without prejudice if, upon reviewing the claim or counterclaim, or at any other time in the proceeding, the Copyright Claims Board concludes that the claim or counterclaim is unsuitable for determination by the Copyright Claims Board, including on account of any of the following: (A) The failure to join a necessary party. (B) The lack of an essential witness, evidence, or expert testimony. (C) The determination of a relevant issue of law or fact that could exceed either the number of proceedings the Copyright Claims Board could reasonably administer or the subject matter competence of the Copyright Claims Board. (g) Service of notice and claims In order to proceed with a claim against a respondent, a claimant shall, within 90 days after receiving notification under subsection (f) to proceed with service, file with the Copyright Claims Board proof of service on the respondent. In order to effectuate service on a respondent, the claimant shall cause notice of the proceeding and a copy of the claim to be served on the respondent, either by personal service or pursuant to a waiver of personal service, as prescribed in regulations established by the Register of Copyrights. Such regulations shall include the following requirements: (1) The notice of the proceeding shall adhere to a prescribed form and shall set forth the nature of the Copyright Claims Board and