New Sidboxes Don't Appear in Layout Box Controller Admin

V 1.2.7

Despite looking over all the FAQs and searching through countless posts in the forum I have not been able to resolve a recurring issue I have with sideboxes. I have tried two install two sidebox modules but they never show up on the list of available sideboxes in the layout box controller admin panel. I recently installed the archived version of the module newsletter subscription so that people can subscribe their emails from a sidebox...the box is still not available in the admin though. Is there something I am missing about activating sideboxes? Or perhaps I have to flush a page cache somewhere for it to show up?? Thanks for any help

PS...i know I should upgrade, but I am waiting for V 2.0 to be fully released

I haven't used that mod, but many mods use a generic folder name (like CUSTOM) in the directory tree, so if you just upload the files and your template isn't named CUSTOM, you won't see the sidebox in admin.

I've gone over it again to make sure that all files were in the right place and they are, but the sidebox still isn't showing up. Last time I tried to install a module w/ sidebox same thing happened. Is there a cache that needs to be flushed when new files are installed? A template cache?

I think perhaps the module just isn't compatible with V1.2.7. I downloaded it from archives and it says 1.5.8 in the read me file. Just as a test I took the who's online sidebox template and swapped out the code to the subscribe template's code. The sidebix finally showed up, but when you enter an email to subscribe you get error messages:

Warning: main(includes/languages/english/html_includes/FILENAME_DEFINE_SUBSCRIBE.php) [function.main]: failed to open stream: No such file or directory in /public_html/store/includes/templates/template_default/templates/tpl_subscribe_default.php on line 40

Warning: main(includes/languages/english/html_includes/FILENAME_DEFINE_SUBSCRIBE.php) [function.main]: failed to open stream: No such file or directory in /public_html/store/includes/templates/template_default/templates/tpl_subscribe_default.php on line 40

Fatal error: main() [function.require]: Failed opening required 'includes/languages/english/html_includes/FILENAME_DEFINE_SUBSCRIBE.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /public_html/store/includes/templates/template_default/templates/tpl_subscribe_default.php on line 40

I'm using zencart 1.3.8 here : https://www.italiancoins.org but to me too it don't apear in admin area to show it in boxes or header, what else I have to do?