Change Record in Table Maintenace using Events

Hi,

I have a z table and have created table maintenanace for it. In my Z table I have below fields.

delivery no

delivery type

created on

created by

changed on

chnged by

When I am creating a new entry. Created on and Created by are geeting filled automatically using Event 05.

But, When I am trying to change the record any field. Change on and changed By are not getting filled in the maintenace screen as well as in database.

Please let me know how we can handle this.

Thanks in Advance.

Vikas