GotoBookmark(pointer(FzhDBGrid1.SelectedRows.Items[j]))问题

[Oyun]

执行该语句出现“变量或者类型不正确，或者不在可以接受的范围之内，要不就是与其它数据冲突。”
同样的语句在别处都没有问题。

[aiirii]

procedure TForm1.btnDoSumClick(Sender: TObject);
var
i: Integer;
sum : Single;
begin
if DBGrid1.SelectedRows.Count > 0 then
begin
sum := 0;
with DBGrid1.DataSource.DataSet do
begin
for i := 0 to DBGrid1.SelectedRows.Count-1 do
begin
GotoBookmark(Pointer(DBGrid1.SelectedRows.Items[i]));
sum:= sum + AdoQuery1.FieldByName('Size').AsFloat;
end;
end;
edSizeSum.Text := FloatToStr(sum);
end
end;

[Oyun]

我的代码大致这样：
if FzhDBGrid1.SelectedRows.Count=0 then
begin
if MessageDlg('只提交选中记录,继续吗?',
mtConfirmation, [mbYes, mbNo], 0) = mrNo then
exit;
for j :=0 to FzhDBGrid1.SelectedRows.Count-1 do
begin
GotoBookmark(pointer(FzhDBGrid1.SelectedRows.Items[j]));
if query6.fieldbyname('submitstate').AsString<>'*' then
begin
append;
for i:=0 to FieldCount-1 do
begin
if (uppercase(Fields[i].FieldName)<>'DETAILID') and
(uppercase(Fields[i].FieldName)<>'ATTEMPERID') and
(uppercase(Fields[i].FieldName)<>'TASKSTATE') and
(uppercase(Fields[i].FieldName)<>'ATTEMPERSTATE') and
(uppercase(Fields[i].FieldName)<>'OLDBUNDLENO') and
(uppercase(Fields[i].FieldName)<>'ISANTISTATIC') and
(uppercase(Fields[i].FieldName)<>'STYLESERIAL')then
fieldbyname(Fields[i].FieldName).Value:=
query6.fieldbyname(Fields[i].FieldName).value;
end;
post;
query6.Edit;
query6.fieldbyname('submitstate').AsString:='*';
end;
end;//for j := 0 to FzhDBGrid1.SelectedRows.Count-1 do
end;

[Oyun]

无法解释，只好结贴了。