get displayed value from listbox or drop-down box by Infopath/sharepoint2010

When get a value from list of drop-down box tied to data-source of sharepoint list and send it to text-box by rule it shows the value of the index.

How can I send displayed value or convert the value of index into displayed value?

add more info;
Thank you for answering. but if change ID to Title, an error of “only positive integers allowed”. refer to custom list form – only positive integer allowed in dropdown. What I originally try to do is prepare 2 drop-boxes(db1, db2) associated with each different field in the a same data-source of a sharepoint list and filter a list of the candidates in db2 by the selected value in db1. Any best practice?
Hiro