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When constructing a sort it's important to get the syntax levels right. Here they are. The Sort is within the sheet and the SortFields are within the Sort and each level is indented by one level, begining to end.
With ActiveWorkbook.Worksheets("Sheet1") ' avoid using "ActiveSheet"
With .Sort
With .SortFields
End With
End With
End With
ActiveSheet is the tab you last looked at. You will stop using this after you ran the code on a wrong sheet by mistake a few times but you are welcome to heed my advice: refer to the sheet by name in your code.
The next thing to avoid is Offset. If you know that you mean A2, don't refer to it as Range("A1").Offset(1). In fact, refer to a cell using cell addressing syntax, a range using range addressing syntax. Cells are addressed by Row & Column coordinates, ranges by their names (you can concatenate a range name from cell references). Avoid using ActiveCell.
With that said, you define the range to sort. In your case that is A1:B35. That includes headers but that's not a problem that you overcome with Offset. Instead you have the Sort property "Headers" which you plan to set as "Yes". It says that the SetRange includes one row of headers.
Now you are reader to set up the SortFields. Start by removing any existing ones. Then understand that a "SortField" is the first cell of a column, not necessarily part of the range to sort. You need to tell Excel to "Sort on column A". "A" is the first column of both your tab and your sort range. Therefore the Sortfield := 1 (or any expression that evaluates to "1"). Bear in mind that sorting will be done on the SortField. Any other columns included in the RangeToSort will remain unsorted, but rows will stay aligned. You can set a second and third Sortfield to first sort on column A, then collumn B etc.
And that's the entire setup. You can now easily adapt the code below to any range and any sheet.
Private Sub SortMyRange()
Dim RngToSort As Range
With ActiveWorkbook.Worksheets("Sheet1") ' avoid using "ActiveSheet"
Set RngToSort = .Range("A1:B35")
Set SortFieldsRng = .Range("A1:B1")
With .Sort
With .SortFields
.Clear
.Add2 Key:=RngToSort.Columns(1), _
SortOn:=xlSortOnValues, _
Order:=xlDescending, _
DataOption:=xlSortNormal
End With
.SetRange RngToSort
.Header = xlYes
.MatchCase = False
.Orientation = xlTopToBottom
.SortMethod = xlPinYin
.Apply
End With
End With
End Sub