(5)The [* * *] [ Omitted by Act 21 of 1998, Section 65 (w.e.f. 1.10.1998).] [Commissioner (Appeals)] [ Inserted by Act 29 of 1977, Section 39 and Schedule V (w.e.f. 10.7.1978).] may, at the hearing of an appeal, allow the appellant to go into any ground of appeal not specified in the grounds of appeal, if the [* * *] [ Omitted by Act 21 of 1998, Section 65 (w.e.f. 1.10.1998).] Commissioner (Appeals) is satisfied that the omission of that ground from the form of appeal was not wilful or unreasonable.