concat validation rules with form_validation

Hi.

I have a doubt about validaton files with form_validation library when concat several rules with pipes(|).

For example. I have an email field that I validate with: required|max_length[15]|valid_email.
Then, if user puts a text with more than 15 characters and in addition isn't valid email, my application only shows error by max_length exceed but like I am using validations_errors() I think that it must show both errors, not?

Is this correct?
For additional info I am using MY_Form_validation extending Form_validation with some custom rules, that I don't know if affects.

Thanks.