My first custom module... Install issue

I’ve built my first custom module. When I go to Add-Ons to install it, everything appears to go fine (a new record is inserted into the “modules” table and all of my custom tables are created just fine), but the add-on is still listed as “Not Installed”. Then when I click to install it again, it will create duplicate records in the “modules” table.

What might I be missing that tells Expression Engine that the module is indeed installed?? I’ve followed the user guide and created all necessary files and there’s no errors being thrown.