Can anyone help me as to why I get a run time error 1004 - Insert method of
Range Class failed
when this bit of code reaches the "Selection" line?

Sub compare()

Row = 1
Do
If (Cells(Row, 1) < Cells(Row, 4)) Then
Cells(Row, 4).Select
Selection.Insert shift:=x1down
Else
Row = Row + 1
End If
Loop Until Row = 20

End Sub