Using VBA to select a group of cells based on same values - vba

Question

I would like write a VBA code to select a group of cells that has the same value and colour it.
MySpreadSheet
For Row A, Staff ID, are the same, for the same person, I intend to scan through them and if they are the same, fill the cells with the light blue colour you see in the picture above, for Column A to MaxColumn of Current Region.
I have a drafted a code to do that but it does nothing when I run it. Any help will be appreciated:
Sub ActualColouring()
Dim SerialNumber As Integer
SerialNumber = 2 'this variable will be assign to the rows, ignore the header, start from 2
Do While Cells(1, SerialNumber).Value <> "" 'keep looping as long as cell is not blank
If Cells(1, SerialNumber).Value = Cells(1, SerialNumber + 1).Value Then 'if the value of the cell is the same as the cell below, then
Cells(1, SerialNumber).Select 'then select it
With Selection.Interior 'this line is the start of the fill colouring
.Pattern = xlSolid
.PatternColorIndex = xlAutomatic
.ThemeColor = xlThemeColorAccent1
.TintAndShade = 0.799981688894314
.PatternTintAndShade = 0
End With 'end of fill colouring function
End If
SerialNumber = SerialNumber + 1 'move to the next cell
Loop 'loop until the end of current region
End Sub

Answer 1

Qualify the objects and avoid select
Sub ActualColouring()
Dim ws as Worksheet
Set ws = ThisWorkbook.Worksheets("mySheet") ' change name as needed
With ws
Dim SerialNumber As Long, lRow as Long
lRow = .Range("A" & .Rows.Count).End(xlup).Row
For SerialNumber = 2 to lRow
If .Cells(1, SerialNumber).Value = .Cells(1, SerialNumber + 1).Value Then
With .Cells(1, SerialNumber).Interior
.Pattern = xlSolid
.PatternColorIndex = xlAutomatic
.ThemeColor = xlThemeColorAccent1
.TintAndShade = 0.799981688894314
.PatternTintAndShade = 0
End With
End If
Next
End With
End Sub