Homepage not loading for new opencart folder created in linux after copying from first one

I had one opencart store in my linux server with one subfolder.i wanted to create a new sub folder other than the first one.I m creating a new folder by copying the files from first one and creating new config files for index and admin folder for new store path..

and after that when i run the homepage of new store.it gives me following error.

call to a member function getUserName() on non-object in admin/controller/header.php line no.-13

but when i m running the admin module for new store.its working fine..

Looks like issue is in config.php file.Please help me if that is also required.as rest all files are same as first folder