Registration Form Validation

Ok so i am trying to implement a username length maximum to 20 and i set that in the ms-functions.php file. The weird thing I noticed was that it still validated with no error messages. Now i tried removing it and putting it back to default and it defaults to have a minimum username length of 4 characters. I tried registering with less than that, and yet it still validates and registers the user.

I dont know why this is, but this function file doesnt seem to be working for registration validation. I do not know why this is, no do i know what to do.

Any ideas?

I want to be able to validate the username field to produce an error message and disallow registration if there are more than 20 characters.