this is caused by the ForwardsOnly property of IQuery which is set by default to true. You need to set it to false and everything will work out fine.
|IQuery query = scope.GetOqlQuery("select * from OrderExtent as x");
| query.ForwardsOnly = false;
| IQueryResult clist = scope.GetOqlQuery(query).Execute();
| RadGrid1.DataSource = clist;
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