我想在数据在流转过程中能退回怎么设置,比如从2A退回1B

Select Case e.DataCol.Name
    Case "第一列","第二列","第三列","第四列","第五列","第六列"
        Dim dr As DataRow = e.DataRow
        Dim jd As String = "1A"
        If dr.IsNull("第一列") = False AndAlso dr.IsNull("第二列") = False Then
            jd = "1B"
            If dr.IsNull("第三列") = False AndAlso dr.IsNull("第四列") = False Then
                jd = "2B"
                If dr.IsNull("第五列") = False AndAlso dr.IsNull("第六列") = False Then
                    jd = "3B"
                End If
            End If
        End If
        If jd = "1B" AndAlso dr("进度") = "2A" Then \'注意这里的处理技巧，意思是2A不能回到1B，3A不能回到2B
        ElseIf jd = "2B" AndAlso dr("进度") = "3A" Then
        Else
            dr("进度") = jd
        End If
End Select