How to lookup No by Type on SalesLine

os2013

A simple question: What’s the trick on i.e. Sales Line (T#37) to actually launch the different list forms. If you look at the field “No.” in the table its properties relates to various tables based on the “Type” field. But if you look at the “Sales Order” sub-form and the text box “No.” the “Look Up” property is set to “No” – so where is it determined which list form to run?

mohana_cse06

It works with the TableRelation property which we set on table 37.

Lookup property on Sales Order Subform No. field is not set to No in Standard.
can you check again please.