Purchase Order Header enhancement - ME_GUI_PO_CUST and ME_PROCESS_PO_CUST

I have enhanced CI_EKKODB in EKKO to add 12 new fields. I've created a custom subscreen in SE80 with those fields.

I've implemented ME_GUI_PO_CUST (ME_PROCESS_PO_CUST was already implemented previously) and put the appropriate code in SUBSCRIBE and MAP_DYNPRO_FIELDS methods. I also put code, which I thought was appropriate in the other methods in the Interface.

I have copied function group MEPOBADIEX into ZMEPOBADIEX and changed the Function Modules to use the Z versions.

When I run ME21N / ME22N / ME23N, I do see my new tab and the fields. I can enter data and switch back and forth through the tabs and my data stays. However, when I try to SAVE, I get the No Data Changed popup.

I have put breakpoints in each of the methods. The breakpoints are only stopping in SUBSCRIBE, MAP_DYNPRO_FIELDS and EXECUTE.

Methods: TRANSPORT_FROM_MODEL, TRANSPORT_TO_DYNP, TRANSPORT_FROM_DYNP, and TRANSPORT_TO_MODEL aren't getting called.

And, by not getting called, it seem my data isn't being transferred back properly.

What's going on? I see this issue over and over online, but no solutions.

thanks,

robert.