problem adding 2 values ​​in 2 columns

everything runs smoothly except at step. adding 2 the value in column 5 and the value in column 7. the result is not correct and the whole program crashes and exits. what's my mistake? the bold is where it goes wrong

Code:

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Private Sub Worksheet_Change(ByVal Target As Range)
Dim lastRow As Long
Dim i As Long
lastRow = ActiveSheet.Cells(Rows.Count, 1).End(xlUp).Row
For i = 11 To lastRow
  If Cells(i, 8) = 0 Then
      If Cells(i, 7) < 1 And Cells(i, 5) < Cells(i, 6) Then
        Cells(i, 5).Interior.Color = RGB(255, 153, 153)
        ElseIf Cells(i, 5) >= Cells(i, 6) Then
        Cells(i, 5).Interior.Color = RGB(255, 255, 255)
        ElseIf Cells(i, 7) >= 1 Then
        Cells(i, 5).Interior.Color = RGB(255, 204, 153)
      End If
  ElseIf Cells(i, 8) >= 1 Then
  Cells(i, 5).Value = Cells(i, 5).Value + Cells(i, 7).Value
  Cells(i, 7).Value = 0
  Cells(i, 5).Interior.ColorIndex = xlColorIndexNone
  End If
    Next i
End Sub

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can you just Create a Conditional Formatting on the Cells, instead of using VBA code.

Code:

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Private Sub Worksheet_Change(ByVal Target As Range)Dim lastRow As Long
Dim i As Long
Application.EnableEvents = False
lastRow = ActiveSheet.Cells(Rows.Count, 1).End(xlUp).Row
For i = 11 To lastRow
    If Val(Cells(i, 8) & "") = 0 Then
        If Val(Cells(i, 7) & "") < 1 And Val(Cells(i, 5) & "") < Val(Cells(i, 6) & "") Then
            Cells(i, 5).Interior.Color = RGB(255, 153, 153)
        ElseIf Val(Cells(i, 5) & "") >= Val(Cells(i, 6) & "") Then
            Cells(i, 5).Interior.Color = RGB(255, 255, 255)
        ElseIf Val(Cells(i, 7) & "") >= 1 Then
            Cells(i, 5).Interior.Color = RGB(255, 204, 153)
        End If
    ElseIf Val(Cells(i, 8) & "") >= 1 Then
        Cells(i, 5) = Val(Cells(i, 5) & "") + Val(Cells(i, 7) & "")
        Cells(i, 7) = 0
        Cells(i, 5).Interior.ColorIndex = xlColorIndexNone
    End If
Next i
Application.EnableEvents = True
End Sub

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Couple of observations

You don't use Target so every change triggers the event handler

You don't turn off EnableEvents inside so it keeps calling itself until Excel gives up

Code:

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Option Explicit

Private Sub Worksheet_Change(ByVal Target As Range)
Dim lastRow As Long
Dim i As Long
lastRow = Cells(Rows.Count, 1).End(xlUp).Row
Application.EnableEvents = False
For i = 11 To lastRow
    If Cells(i, 8) = 0 Then
      If Cells(i, 7) < 1 And Cells(i, 5) < Cells(i, 6) Then
          Cells(i, 5).Interior.Color = RGB(255, 153, 153)
      ElseIf Cells(i, 5) >= Cells(i, 6) Then
          Cells(i, 5).Interior.Color = RGB(255, 255, 255)
      ElseIf Cells(i, 7) >= 1 Then
          Cells(i, 5).Interior.Color = RGB(255, 204, 153)
      End If
  ElseIf Cells(i, 8) >= 1 Then
      Cells(i, 5).Value = Cells(i, 5).Value + Cells(i, 7).Value
      Cells(i, 7).Value = 0
      Cells(i, 5).Interior.ColorIndex = xlColorIndexNone
  End If
Next i
Application.EnableEvents = True
End Sub

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