APEX

Hi All,
Has anyone used apex_exec API with the classic report?
I am getting invalid number an error every time when I use the following PL/SQL code on line 

v_context := apex_region.open_query_context (p_page_id => :APP_PAGE_ID,
                                             p_region_id => v_region_id);

select region_id
      into v_region_id
      from apex_application_page_regions
     where application_id = :APP_ID
       and page_id = :APP_PAGE_ID
       and static_id = 'my_static_id';

  -- Get the query context for the report
  v_context := apex_region.open_query_context (p_page_id => :APP_PAGE_ID,
                                               p_region_id => v_region_id);

v_id := apex_exec.get_column_position(v_context, 'MY_COLUMN_NAME');

I am using this piece of code in a page process to fetch all data and update values in DB. I am using APEX 20.2 and 18c DB.
Let me know if anything is wrong with this logic?
Thanks