행 삽입 매크로에서 디버그 오류가 뜹니다.

Option Explicit
 
Sub Shiftrows()
    Dim lastRow As Long
    Dim i As Long
    Dim ShiftCount As Long
 
    lastRow = Cells(Rows.Count, "a").End(xlUp).Row
 
    For i = lastRow To 1 Step -1
 
        ShiftCount = Cells(i, "a").Value - 1
 
        If IsNumeric(ShiftCount) And ShiftCount >= 1 Then
            Cells(i + 1, 1).Resize(ShiftCount, 1).Insert Shift:=xlDown, _
                CopyOrigin:=xlFormatFromLeftOrAbove
        End If
    Next i
End Sub
 
'또는
 
Sub 행삽입()
    Dim iLastRow As Integer, i As Integer
    Dim r As Range
 
    iLastRow = Sheet1.Cells(Rows.Count, 1).End(xlUp).Row
    With Sheet1
        For i = iLastRow To 2 Step -1
            Set r = .Cells(i, 1)
            r.Offset(1, 0).Resize(r.Value - 1, 1).Insert Shift:=xlDown, _
                CopyOrigin:=xlFormatFromLeftOrAbove
        Next i
    End With
End Sub