请各位帮我看看这段代码哪里出错了.非常感谢!
这是一段删除某个对象的代码,执行删除后,报内存非法访问错:Raised exception class EAccess Violation with Message 'Access violation at address xxxxxx in module '
procedure TFrmMain.ToolButton9Click(Sender: TObject);
var
    ii,j:integer ;
    deletechart:string;
    queryc:TADOQuery;
begin
try
queryc:=TADOQuery.Create(self);
queryc.Connection :=dbprocess.acprocess ;
  for ii:=0 to (UntMain.FrmMain.ComponentCount-1) do
    begin
     if  UntMain.FrmMain.Components[ii] is  TRectBox then
       begin
        re:=TRectBox(FrmMain.Components[ii]);
        deletechart:=re.Name;
          with  queryc do
           begin
             if midstr(deletechart,1,3)='Uob' then /////////////删除活动图信息
             begin
             uob:=Tuob(FrmMain.Components[ii]);
             if uob.Focus then
             begin
               close;
               sql.Clear ;
               sql.Text :='select * from uob where uob_id='''+deletechart+'''and model_id='''+model_id+'''';
               open;
               if recordcount=0 then
                begin
                 combobox1.Items.Delete(combobox1.Items.IndexOf(re.Name));
                 combobox1.text:='';
                 VLE.Strings.Clear;
                 for j:=0 to treeview1.Items.Count-1 do
                 begin
                    if treeview1.Items[j].Text=re.Caption then
                    begin
                    treeview1.Items.Delete(treeview1.Items[j]);
                    break;
                    end;
                 end;
                 uob:=nil;
                 re.Destroy;
                 break;
                end
               else
                 begin
                 combobox1.Items.Delete(combobox1.Items.IndexOf(re.Name));
                 combobox1.text:='';
                 VLE.Strings.Clear;
                 for j:=0 to treeview1.Items.Count-1 do
                 begin
                    if treeview1.Items[j].Text=re.Caption then
                    begin
                    treeview1.Items.Delete(treeview1.Items[j]);
                    break;
                    end;
                 end;
                   with queryc do
                    begin
                     close;
                     sql.Clear ;
                     sql.Text :='delete * from uob where uob_id='''+deletechart+'''and model_id='''+model_id+'''';
                     execsql;
                   end;
                   uob:=nil;
                   re.Destroy ;
                   break;
                 end;
              end;