what I did to get this response is:
-- duplicate /usr/local/ispconfig/interface/web/help to /usr/local/ispconfig/interface/web/drupispc
-- change all the appearances of the word "help" with the word "drupispc", and the word "message" with the word "act" (even in the fine names).
-- try to use the "send" form
The reason for your problem is that you duplicated the whole module instead of creating just the form and ..._edit.php files. The database table gets created together with the templates file in the "template" subfolder. If the temnplate is already there, then no database table geats created. Rebname or remove the template file for the edit form from the templates folder and open the edit file again in the webbrowser.
What I imagine for this module, roughly speaking, is a button (create drupal) next to a websites listbox (in this case example.com chosen), on click:
# mkdir /var/www/example.com/drupalsite
# mkdir /var/www/example.com/drupalsite/files
# mkdir /var/www/example.com/drupalsite/themes
# mkdir /var/www/example.com/drupalsite/modules
# cp -a /var/www/sites/default/default.settings.php /var/www/example.com/drupalsite/settings.php
# ln -s /var/www/example.com/drupalsite /var/www/sites/example.com
# chown ...
# chmod ...
Interface modules dont have access to the website directories, so they can do these steps. What you will have to do is to create a server plugin beside the interface module for that, as only server plugins have the nescessary permissions to create folders inside a website.
So the steps are:
1) Create a interface module to show your forms and lists in the ispconfig interface.
2) Create a "module" file in the server part that adds events to the server side event system when a item is inserted or updated in your new database table. See server/mods-available folder for examples.
3) Create a server side plugin that listens to these events and does the actions required to install drupal. See server/plugins-available directory for examples.