Problem with range for copy paste

[clng75]

This works:-

 Worksheets("GSP raw data").Range("A1:C1").Copy Worksheets("Transposed GSP Data").Range("A1:C1")

How do I make this to similar short? I am unable to make this work

 Sheets("GSP raw data").Range(Cells(iRow, 1), Cells(iRow, 3)).Copy  Sheets("Transposed GSP Data").Range( Cells(N1, 1))

The selection.autofill also does not work if I do not specify the worksheets and cells.

For iRow = 3 To O1
        
        Sheets("GSP raw data").Range(Cells(iRow, 1), Cells(iRow, 3)).Copy
        
        Sheets("Transposed GSP Data").Select
        N1 = Sheets("Transposed GSP Data").Cells(Rows.Count, 1).End(xlUp).Row + 1 ' find the last recent row to append data
                   
                    
                    NiRow = N1 + CLng(23) ' find the next "24" months to add new linr items (24 motnhs for 2 FY)
                    Cells(N1, 1).Select
                    ActiveSheet.Paste

                    Selection.AutoFill Destination:=Range(Cells(N1, 1), Cells(NiRow, 3)), Type:=xlFillDefault
  
                    
                    Application.CutCopyMode = False
                    
                    ' auto-fill the row information down for 24 months
                    Selection.AutoFill Destination:=Range(Cells(N1, 1), Cells(NiRow, 3)), Type:=xlFillDefault

                    
                    Application.CutCopyMode = False

Thanks in advance

[DannyJ]

DCould you please post a desensitized example of your workbook and how the code should work.