Each time I try to set the variable 'Header' in the below code it retruns nothing. Could someone help in indentifying why this is happening?

Question

Sub Import_Data()

Dim WB As Workbook
Dim WS As Worksheet
Dim Start_Row As Byte, Last_Row As Byte, Next_Row As Byte, Counter As Byte, C As Byte
Dim File As Variant
Dim Header As Range

'Import the data of each file into the NewData tab

With shNewDat
     .Cells.Clear
     .Activate
End With

File = Application.GetOpenFilename("Excel files (.xlsx), *.xlsx", , "Select your files", , True)

If IsArray(File) Then
   For Counter = 1 To UBound(File)
   
   Set WB = Workbooks.Open(File(Counter))
   Set WS = WB.ActiveSheet
   
       If Counter = 1 Then
          WS.Range("B4").CurrentRegion.Copy shNewDat.Range("B1")
          Last_Row = shNewDat.Range("B1").End(xlDown).Row
          shNewDat.Range("A1") = "Company_ID"
          WS.Range("C2").Copy
          shNewDat.Range("A2:A" & Last_Row).PasteSpecial xlPasteValues
       
       Else
          Next_Row = shNewDat.Range("B1").End(xlDown).Row + 1
          WS.Range("B5").CurrentRegion.Offset(1).Copy shNewDat.Range("B" & Next_Row)
          Last_Row = shNewDat.Range("B1").End(xlDown).Row
          WS.Range("C2").Copy
          shNewDat.Range("A" & Next_Row, "A" & Last_Row).PasteSpecial xlPasteValues
          
       End If
       
       WB.Close False
       
   Next Counter
             
End If
       
'Import the data from the NewData tab into the Summary tab

C = 1

Do Until shAll.Cells(1, C).Value = ""
   
   Set Header = shNewDat.Rows(1).Find(what:=shAll.Cells(1, C).Value, LookIn:=xlValues, MatchCase:=False, lookat:=xlWhole)

   shNewDat.Range(Cells(2, Header.Column), Cells(Range("A1").End(xlDown).Row, Header.Column)).Copy shAll.Cells(2, C)

Loop

End Sub