Управление товарно-материальными запасами в Excel VBA

Question

Sub Data()
    Dim ItemName As Variant
    Dim FinalRow As Long
    Dim i As Long


    ItemName = Sheets("Sheet3").Range("B4").Value
    FinalRow = Sheets("Sheet1:Sheet2!B3:B10").Row


    For i = 3 To FinalRow

    If Cells(i, 2) = ItemName And Cells(i, 4) = "" And Cells(i, 5) = "sheet1" Then

  Range(Cells(i, 3)).Copy

  Range("B3", Range("B3").End(xlDown)).PasteSpecial Paste:=xlPasteAll, Operation:=xlPasteSpecialOperationAdd, SkipBlanks:=False, Transpose:=False

            If Cells(i, 2) = ItemName And Cells(i, 4) = "" And Cells(i, 5) = "sheet2" Then
                Range(Cells(i, 3)).Copy

                Range("B3", Range("B3").End(xlDown)).PasteSpecial   Paste:=xlPasteAll, Operation:=xlPasteSpecialOperationAdd, SkipBlanks:=False, Transpose:=False
                ElseIf Cells(i, 2) = ItemName And Cells(i, 3) = "" And Cells(i, 5) = "sheet1" Then
    enter code here
                Range(Cells(i, 4)).Copy
                Range("B3", Range("B3").End(xlDown)).PasteSpecial Paste:=xlPasteAll, _
                Operation:=xlPasteSpecialOperationAdd, SkipBlanks:=False, Transpose:=False
                Else:
                End If
    enter code here
    ElseIf Cells(i, 2) = ItemName And Cells(i, 3) = "" And Cells(i, 5) = "sheet1" Then
            Range(Cells(i, 4)).Copy
            Range("B3", Range("B3").End(xlDown)).PasteSpecial Paste:=xlPasteAll, _
            Operation:=xlPasteSpecialOperationAdd, SkipBlanks:=False, Transpose:=False
    Else:
    End If
    Next i       
End Sub

'''the code does not seems to work any help much appreciated