Can not Create Master-Detail report

Tim

i can not Create Master-Detail report

---

1 Fast report version 2.5 vcl
2 mysql database
3 dbexpress connection

my report create band
1 masterdata band
datasource=Query1 (master data table)
2 subdetail data band
datasource=Query2 (detail data table)

sql on query command
1 Query1.sql='select * from header'
2 Query2.sql='select * from detail where (docno=:docno)'

link field master --> detail
Query2.Datasource=Query1
Query2.parambyname('docno').asstring=Query1.fieldbyname('docno').asstring;

on preview report error message:=
"Query2 :Cannot perform this operation on a close dataset."

thank you for any idea
tim