Macro that only works when you open the paste function wizard????

I took a formula I use and tried to create a macro with it.  For some reason it does not work with the macro, but works fine if the formula is applied to the cells directly.  Also, if I goto a cell and then hit the paste function button, the macro gets applied.  Is this an excel flaw or more likely poor coding of the macro.. Please help.

Here is the macro I created:

Sub Create_unmatched_Credits_report_from_detailed_AR_Report()
'


'
    Range("A1").Select
    Selection.EntireColumn.Insert
    Range("A1").Select
    ActiveCell.FormulaR1C1 = "Lookup Column"
    Selection.Font.Bold = True
    Selection.Font.ColorIndex = 3
   
    Range("A2").Select
    ActiveCell.FormulaR1C1 = "=+RC[1]&RC[6]&RC[13]"
   
    Selection.Copy
    ActiveCell.SpecialCells(xlLastCell).Select
    Selection.End(xlToLeft).Select
    Selection.End(xlToLeft).Select
    Selection.End(xlToLeft).Select
    Selection.End(xlToLeft).Select
    Range(Selection, Selection.End(xlUp)).Select
    ActiveSheet.Paste

    Selection.Font.Bold = True
    Selection.Font.ColorIndex = 3
   
   
   
   
   
ActiveCell.SpecialCells(xlLastCell).Select
    Selection.End(xlToLeft).Select
    Range("P28").Select
    Selection.End(xlDown).Select
    Selection.End(xlUp).Select
    With Selection.Interior
        .ColorIndex = 15
        .Pattern = xlSolid
        .PatternColorIndex = xlAutomatic
    End With
    Selection.Borders(xlDiagonalDown).LineStyle = xlNone
    Selection.Borders(xlDiagonalUp).LineStyle = xlNone
    With Selection.Borders(xlEdgeLeft)
        .LineStyle = xlContinuous
        .Weight = xlThin
        .ColorIndex = 48
    End With
    Selection.Borders(xlEdgeTop).LineStyle = xlNone
    Selection.Borders(xlEdgeBottom).LineStyle = xlNone
    With Selection.Borders(xlEdgeRight)
        .LineStyle = xlContinuous
        .Weight = xlThin
        .ColorIndex = 48
    End With
    Selection.Borders(xlInsideVertical).LineStyle = xlNone
    Selection.Borders(xlInsideHorizontal).LineStyle = xlNone
    With Selection
        .HorizontalAlignment = xlRight
        .VerticalAlignment = xlTop
        .WrapText = False
        .Orientation = 0
        .AddIndent = False
        .ShrinkToFit = False
        .ReadingOrder = xlContext
        .MergeCells = False
    End With
    Selection.NumberFormat = "General"
    ActiveCell.FormulaR1C1 = "Should be examined?"
    With ActiveCell.Characters(Start:=1, Length:=19).Font
        .Name = "Courier New"
        .FontStyle = "Regular"
        .Size = 10
        .Strikethrough = False
        .Superscript = False
        .Subscript = False
        .OutlineFont = False
        .Shadow = False
        .Underline = xlUnderlineStyleNone
        .ColorIndex = xlAutomatic
    End With
    Range("P1").Select
    Selection.Font.Bold = True
    Selection.Font.ColorIndex = 3
   
    Range("P2").Select
    ActiveCell.FormulaR1C1 = "=IF(ISERROR(VLOOKUP(rc[-14]&""INV""&(rc[-2]*-1),A:O,1,FALSE)),""No"",""Yes"")"
    Range("P2").Select
       
   

End Sub