Application Express :: Custom Download Procedure Not Working?

I have created a custom download procedure to download uploaded files from custom table records which are displayed via links and i call my procedure as #OWNER#.my_file?p_file=#ID#. Now the problem this procedure call works in my development system not any other system.

is there any grant i need to provide but i don't want to grant to public also apex 4.1.1  create or replace PROCEDURE

my_file(p_file in number) AS        v_mime  VARCHAR2(500);        v_length  NUMBER;        v_file_name VARCHAR2(400);        Lob_loc  BLOB;BEGIN    SELECT trim(MIME_TYPE), BLOB_CONTENT, trim(filename),DBMS_LOB.GETLENGTH(blob_content)          INTO v_mime,lob_loc,v_file_name,v_length      FROM EMP.FILE_attachments                WHERE id = p_file;     owa_util.mime_header( nvl(v_mime,'application/octet'), FALSE );        htp.p('Content-length: ' || v_length);     htp.p('Content-Disposition:  attachment; filename="'||replace(replace(substr(v_file_name,instr(v_file_name,'/')+1),chr(10),null),chr(13),null)|| '"');  owa_util.http_header_close;                wpg_docload.download_file( Lob_loc ); ---------------------------------