VBA sort row by dates - excel

Question

I have a file containing dates on the first row, and a column of identifiers defining a table where I fill in the employee data for the corresponding data (See picture)
I want the dates to be sorted in the chronological order, but I only want to sort the dates, before I fill in the table.
I tried the following code
Sub sortByDates()
Dim sumSheet as Worksheet
Dim toSort as Range
Set sumSheet = ThisWorkbook.ActiveSheet
LastCol = sumsheet.Cells.Find(What:="*", After:=[a1], _
SearchOrder:=xlByColumns,
SearchDirection:=xlPrevious).Column
Set toSort = sumsheet.Rows(1).Resize(1, LastCol - 1).Offset(0, 1)
toSort.Select
ActiveWorkbook.Worksheets("Employees").Sort.SortFields.Clear
ActiveWorkbook.Worksheets("Employees").Sort.SortFields.Add Key:=toSort, SortOn:=xlSortOnValues, Order:=xlAscending, _
DataOption:=xlSortNormal
With ActiveWorkbook.Worksheets("Employees").Sort
.SetRange toSort
.Header = xlGuess
.MatchCase = False
.Orientation = xlLeftToRight
.SortMethod = xlPinYin
.Apply
End With
End Sub
However the dates moves but don't order as I wish. I think this might have to do with the fact that Excel Sort doesn't know how to handle the dates format, but not sure.

Answer 1

You should define the format of the data to be sorted. After this line in your code, toSort.Select, add this command:
Selection.NumberFormat = "[$-409]d-mmm-yy;#"
(change the format with appropriate one you use)
Here is the code I used and tested: I got the columns sorted correctly
(change feuil1 to your sheet name)
Sub sortByDates()
Dim sumSheet As Range
Dim toSort As Range
'Set sumSheet =
LastCol = ThisWorkbook.ActiveSheet.Cells.Find(What:="*", After:=[a1], SearchOrder:=xlByColumns, SearchDirection:=xlPrevious).Column
Set toSort = ThisWorkbook.ActiveSheet.Rows(1).Resize(1, LastCol - 1).Offset(0, 1)
toSort.Select
Selection.NumberFormat = "[$-409]d-mmm-yy;#"
ActiveWorkbook.Worksheets("feuil1").Sort.SortFields.Clear
ActiveWorkbook.Worksheets("feuil1").Sort.SortFields.Add Key:=toSort, SortOn:=xlSortOnValues, Order:=xlAscending, _
DataOption:=xlSortNormal
With ActiveWorkbook.Worksheets("feuil1").Sort
.SetRange toSort
.Header = xlGuess
.MatchCase = False
.Orientation = xlLeftToRight
.SortMethod = xlPinYin
.Apply
End With
End Sub