51. Consequence of failure to take steps for issue of fresh notice.- Where, after a summon has been issued to the other side, and returned unserved, and the applicant or petitioner or appellant, as the case may be, fails to take necessary steps within the period as ordered by the Appellate Tribunal from the date of return of the notice on the respondent(s), the Registrar shall post the case before the Appellate Tribunal for further directions or for dismissal for non-prosecution.