Issue with GET and SET parameters in BI-ABAP field exits

There is a requirement that in a field for a query in transaction RSRT the value of the field should be auto-populated with the value that was entered when the query was run the last time. For this, GET and SET PARAMETER IDs are used. But the problem is that the parameter is not getting set and no value is populated in the query field. Proper positioning of the set parameter in the code can help to resolve this issue. Request you to throw some light on this.