How to create new shipping modules?

[shrimp-gumbo-mmmhhh]

In the past I created new shipping modules by taking the flat.php shipping module renaming to first.php, priority.php and express.php and then changing all instances of flat to "first", "priority" and "express" and this worked fine.... however, now when I do this nothing happens... I cannot see the new module I added. What am I now missing?

[twitchtoo]

You remembered to add a twin named language file for each shipping module right?

[shrimp-gumbo-mmmhhh]

Okay, I have put a converted database on top of a new install. It appears the problem is that the names are already in the config table.... so i renamed to express2019 and now can see them....

[shrimp-gumbo-mmmhhh]

Thank you twitch.... didn't do that but saw the error posted on my admin.

[twitchtoo]

If I understand correctly, removing the shipping module and adding it back would correct the old/new problem. However I have seen add/remove fail to remove the database tables correctly and create a host of difficult to trace problems as a result.

Be certain the add table text is changed for upper and lowercase appropriately with the new module to prevent cross writing old-new tables.