Form Validation validating default value

[eluser]cmark[/eluser]
Hi there, im getting problems during the validation process:

Code:

$this->form_validation->set_rules('titulo', 'Titulo', 'required');

In the View, i used the set_value function, but when i attempt in order to validate, the form_validation doesn't found any problem with the default value (in this case, 'Titulo').
What can i do?

Ps: sorry with my eng, i'm really very new.

Thanks!