Hi
This is not an error, when ever you receive message " there is backend text associated...." click on 'NO'.
I guess your data list has bound with AccountingEntry, top in right side, then you can not bind any other datafield from other node.
In your case your binding SetofBookid from different node( SetOfBook).
You just bind data field under Data list with the element under only AccountingEntry.
regard
Sunil