关于msgbox的问题

我通过for 循环嵌套来查找两个表中相同的记录，想在查找出相同记录时通过msgbox来进行提示，应该如何解决呀，谢谢老师们指点。

For itemp1 = 0 To rs1.RecordCount - 1
           rs.MoveFirst
           Xtong = False
           For itemp = 0 To rs.RecordCount - 1
               If rs("学号") = rs1("学号") And rs("课程编号") = rs1("课程编号") Then
                  Xtong = True
                  a = rs("学号")
                  b = rs("课程编号")
                  MsgBox "学号为'a'的学生已经选过编号为'b'的课程", vbOKOnly, "选课重复"
                  itemp = rs.RecordCount + 1
                End If

                rs.movenext
            Next itemp
            If Xtong = False Then
               '将选课信息添加到选课表中
               rs.AddNew
               rs("学号") = rs1("学号")
               rs("姓名") = rs1("姓名")
               rs("班级编号") = rs1("班级编号")
               rs("课程编号") = rs1("课程编号")
               rs("课程名称") = rs1("课程名称")
               rs("开课学期") = rs1("开课学期")
               rs.Update

            end if

        rs1.movenext
        Next itemp1