Hi,

<----------- start code ------------->
IBQuery2.SQL.Add( 'select sum(sevkdetail.sevkadeti) as
top_sevki,extract(week from sevkdetail.sevktarihi)as sevk_ayi from
sevkdetail ');
IBQuery2.SQL.Add( 'where sevktarihi>='''+datetostr
(DateTimePicker1.date)+''' AND sevkdetail.sevktarihi<='''+datetostr
(DateTimePicker2.date)+''' ');
IBQuery2.SQL.add('GROUP BY extract(week from
sevkdetail.sevktarihi)' );

<----------- end code ------------->

As far as I can see, I *think* your problem is using a function at your
group by clause, try this instead:

IBQuery2.SQL.add('GROUP BY 2' );


where 2 is the column position of "extract(week from sevkdetail.sevktarihi)"
at your select


Regards,
Anderson Farias