CI3 form validation error on 1and1

Ok, thank's for the answer, you are right, for the case, I made mistake !

But I renamed the file as 'MY_Form_validation.php'.

I verified all the case, but I get the same error.

Code:

A PHP Error was encountered

Severity: Error

Message: Cannot access protected property MY_Form_validation::$CI

Filename: controllers/Prospects.php

Line Number: 11

Backtrace: