又一个奇怪的问题？（急）

Project P_lw.exe raised exception class EOleException with message'无法为更新行集定位：一些值可能已在最后读取后改变。‘不知道问题出在post前还是post后。
procedure TDataModule1.ADOQuery_sjBeforePost(DataSet: TDataSet);
var
 xlh:Integer;
 exte:string;
begin//特殊字段：时间 ,序号
DataModule1.ADOQuery_sj.Fields.Fields[7].AsDateTime:=f_lw.DateTimePicker_sj.DateTime;
DataModule1.ADOQuery_sj.Fields.Fields[11].AsString:=f_lw.OpenDialog.FileName;
xlh:=DataModule1.ADOQuery_sj.Recordcount+1;
case passwordDlg.ComboBox_yh.ItemIndex of
  0:DataModule1.ADOQuery_sj.Fields.Fields[0].AsString:='JLC'+'_'+IntToStr(xlh)+'_'+IntToStr(random(1000))+ExtractFileExt(f_lw.OpenDialog.FileName);
  1:DataModule1.ADOQuery_sj.Fields.Fields[0].AsString:='JZS'+'_'+IntToStr(xlh)+'_'+IntToStr(random(1000)) +ExtractFileExt(f_lw.OpenDialog.FileName);
  2:DataModule1.ADOQuery_sj.Fields.Fields[0].AsString:='LZS'+'_'+IntToStr(xlh)+'_'+IntToStr(random(1000)) +ExtractFileExt(f_lw.OpenDialog.FileName);
  3:DataModule1.ADOQuery_sj.Fields.Fields[0].AsString:='ZBS'+'_'+IntToStr(xlh)+'_'+IntToStr(random(1000)) +ExtractFileExt(f_lw.OpenDialog.FileName);
  4:DataModule1.ADOQuery_sj.Fields.Fields[0].AsString:='YYS'+'_'+IntToStr(xlh)+'_'+IntToStr(random(1000)) +ExtractFileExt(f_lw.OpenDialog.FileName);
  5:DataModule1.ADOQuery_sj.Fields.Fields[0].AsString:='NJS'+'_'+IntToStr(xlh)+'_'+IntToStr(random(1000))  +ExtractFileExt(f_lw.OpenDialog.FileName);
  6:DataModule1.ADOQuery_sj.Fields.Fields[0].AsString:='TFS'+'_'+IntToStr(xlh)+'_'+IntToStr(random(1000)) +ExtractFileExt(f_lw.OpenDialog.FileName);
  7:DataModule1.ADOQuery_sj.Fields.Fields[0].AsString:='XXS'+'_'+IntToStr(xlh)+'_'+IntToStr(random(1000)) +ExtractFileExt(f_lw.OpenDialog.FileName);
  8:DataModule1.ADOQuery_sj.Fields.Fields[0].AsString:='HSS'+'_'+IntToStr(xlh)+'_'+IntToStr(random(1000)) +ExtractFileExt(f_lw.OpenDialog.FileName);
end; if  (f_lw.OpenDialog.FileName<>'') then
beginf_lw.NMFtp.Connect;
f_lw.NMFTP.Upload(f_lw.OpenDialog.Filename,DataModule1.ADOQuery_sj.Fields.Fields[0].AsString);
f_lw.NMFtp.DisConnect;end
else
 ShowMessage('保存记录前，请务必选择论文正文文件！'); 
end;