i am getting this error while running this code wahts wrong please help

Sub Loop8()

Range("D1").Select
Do
If IsEmpty(ActiveCell.Offset(0, -1)) Then
ActiveCell.Value = 0
ActiveCell.Offset(0, -1).Value = "Customer"
ElseIf ActiveCell.Offset(0, -1).Value = ActiveCell.Offset(-1,
-1).Value Then
ActiveCell.Value = 0
Else
ActiveCell.Value = ActiveCell.Offset(0, -2).Value -
ActiveCell.Offset(0, -3).Value
End If
ActiveCell.Offset(1, 0).Select
Loop Until IsEmpty(ActiveCell.Offset(0, -2))



End Sub