Rails couldn't find a valid model for Preferences association

Question

I'm trying to add new record to my DB, but I got this error:

This is my schema.rb:

And this is my method create:

And this is my form to add a new record:

The param is sending correctly, but when I click on Upload button, nothing is happen, and if I try to add the record from the rails console, I got the error of the first image. I'm a new dev of RoR, someone can help me please?, Thanks!!