Call to undefined method Site_model::userd() I do not get it

[eluser]Michal1[/eluser]
Hey guys,

I have a problem with function in site controller. I am inserting a data into database and I have an easy function in my controller

Code:

function create_user()
                {
                    $users = array(
                        'username'=>$this->input->post('username'),
                        'password'=>$this->input->post('password')
                    
                    );
                    
                    $this->site_model->userd($users);
                    
                }

Then I have model: site_model and inside

Code:

function userd($users)
        {
            $this->db->insert('users,$users');
            return;
            
        }

Then when I enter data into inputs and click on submit in my view I get this:

Code:

Fatal error: Call to undefined method Site_model::userd() in........

Why? Everything seems fine to me in the code.

Thank you