Your result in sheet3 is very confusing.
53DFS1I
appears on both sheets, so how come it appears on sheet3 as a missing item?
All sheet 2 lines, except BAMAP2I appear in sheet2. Are you comparing both sheets? Missing items can come only from sheet1(All items of sheet2, except BAMAp2i appear in sheet).
sheet 4 is correct in a sense these two items are missing from sheet1