0mat_sales datasource enhancment problem

<b>Datasource:</b> 0MAT_SALES_ATTR

<b>Goal:</b> I am trying to enhance the datasource with the following fields: (restricted by the condition type and getting only the current valid rate.)

From table ZA004: (an extract of the pool table A004)

KSCHL, KNUMH, DATBI, DATAB

From KONP:

KBETR, KONWA

The ABAP piece isn't a problem (keys, join and selection works), and I have created the append structure, ZABIW_MVKE_S, which activates fine, like this:

ZZKBETR - KBETR Ref: TCURC - WAERS

ZZKSCHL - KSCHL

ZZKNUMH - KNUMH

ZZDATBI - DATBI

ZZDATAB - DATAB

This checks and activates OK, along w/ my ABAP code. However, in RSA6, when I go in and edit 0MAT_SALES_ATTR and try to unhide the KBETR field, it gives me the error:

<i>The OLTP source still has errors

Message no. R8 417</i>

The only note I find on this is 202162 - R8003: IO of type KYF requires unit field.

However, I can't figure out what I am doing wrong. Can anyone suggest what I am missing or doing incorrectly ???

Thanks,

Stephen