奇怪的问题, 大家有没有遇到过

执行完下面的代码后, 把当前的Form给关闭了, 这是怎么回事呀
  try
     dh:=trim(aqMaster['hddh']);
     dm.Connection.BeginTrans ;
     aqMaster.Delete ;
     with ADOCommand1  do
     begin
       Close;
       CommandText:='delete from actname where hddh='''+dh+'''';
       Execute;
     end;
     dm.Connection.CommitTrans ;
  except
    dm.Connection.RollbackTrans ;
    showmessage('Ω埃巨ア毖');
  end;