Short answer. Yes. When the person you want to bring in as a third-party defendant cannot be located within thirty calendar days from the grant of leave to file, the court denies admission of the third-party complaint and requires you to pursue that claim for contribution, indemnity, or subrogation in a separate action instead.
What the law says
the third (fourth, etc.)-party defendant cannot be located within thirty calendar days from the grant of such leave
Rule 6, Section 11 — Third, (fourth, etc.). Read the full provision →
What a third-party complaint is for
A third-party complaint lets a defending party, with leave of court, bring in someone who is not yet a party to the case — for contribution, indemnity, subrogation or any other relief connected to the claim already made against them. Instead of paying a judgment and then filing a whole new lawsuit to recover from the person who should ultimately bear the loss, the defendant can fold that claim into the pending case, provided the court grants leave to do so. The leave-of-court requirement is what gives the judge the checkpoint to apply the rule's limits before a stranger is pulled into the case.
Why the court can refuse to admit it
That convenience has limits. The rule requires the court to deny admission of the third-party complaint, and to direct the defendant to institute a separate action, in three situations: the proposed third-party defendant cannot be located within thirty calendar days from the grant of leave; the complaint raises matters extraneous to the issues in the main case; or admitting it would introduce a new and separate controversy into the action. Each of these protects the same interest — keeping the original case from being derailed by a claim that cannot practically or fairly be tried alongside it. Note that the thirty days are counted in calendar days, and they run from the grant of leave, not from the filing of the motion asking for it.
What happens once the complaint is denied
If the third-party defendant genuinely cannot be located within that thirty-day window, the court will not let the case wait indefinitely for service to be effected. Instead, the defendant is required to pursue the contribution, indemnity, subrogation, or other relief in a separate action filed on its own, once the person can eventually be found and served there. The main case proceeds without that party, so the inability to locate one respondent does not hold up resolution of the claim already before the court. Denial on this ground is about timing and practicality, not the merits: it does not decide whether the person actually owes you contribution or indemnity, and it does not extinguish the claim you would bring in the separate suit.