Set Message in form validation for Certain Input Name

[eluser]edidiway[/eluser]
Hi, I have problem in setting error message for codeigniter.

Generally, Codeigniter will give this error message :

The Mobile Phone field is required.
The Agreement field is required.

I want the error message become like this :

The Mobile Phone field is required.
The Agreement field must be checked

is there any simple ways to do that? because in every form validation, this things always happen, and I want to fix this in the simplest way. I can use callback function if I want, but I fill this is not the simplest way..

if I use this code

Code:

$this->form_validation->set_message('required', 'This Error Message was global for all required Rules');

All Required Rules will get the same error message and I dont want that..