QTP Script 32 - How to compare two excel files and highlight the cells with different values in the first file?

Excel object is being created here
Set Exl_Obj = CreateObject("Excel.Application")
Exl_Obj.Visible = True

Two files sac1 and sac2 are opened
Set WB_Obj_1= Exl_Obj.Workbooks.Open("C:\sac1.xls")
Set WB_Obj_2= Exl_Obj.Workbooks.Open("C:\sac2.xls")

Cells in the first sheet of both the files are compared
Set WS_Obj_1= WB_Obj_1.Worksheets(1)
Set WS_Obj_2= WB_Obj_2.Worksheets(1)

   For Each cell In WS_Obj_1.UsedRange
   If cell.Value <> WS_Obj_2.Range(cell.Address).Value Then
       cell.Interior.ColorIndex = 6
   Else
       cell.Interior.ColorIndex = 0
   End If
Next

Exl_Obj.workbooks("sac1.xls").save
Exl_Obj.workbooks("sac1.xls").close
Exl_Obj.workbooks("sac2.xls").save
Exl_Obj.workbooks("sac2.xls").close
Exl_Obj.Application.Quit
set Exl_Obj=nothing