The appellate authority may, for reasons to be recorded in writing either annul, reverse, modify or confirm the order appealed from, or may direct the officer making the order by himself or by any of his subordinate officers, to make further inquiry or to take additional evidence on such points as the appellate authority may specify, or the appellate authority may itself make such inquiry or take such additional evidence:
Provided that no additional evidence, whether oral or documentary shall be directed to be taken, unless,—
(a) the Revenue Officer from whose order the appeal is preferred has refused to admit evidence which ought to have been admitted, or
(b) the appellate authority requires any document to be produced or any witness to be examined to enable it to pronounce orders, or
(c) for any substantial cause the appellate authority allows such evidence or document to be produced or witness to be examined:
Provided further that when additional evidence is allowed to be produced, by an appellate authority, such authority shall record the reason for its admission.