Help with login function

[eluser]jrad[/eluser]
I'm having problems with my login in CI. I'm really in dire need of help to check on my custom login function. Here's part of the code:

Code:

function login()
    {
        $username = $this->input->post('username');
        $password = $this->input->post('password');
            
        if ($username = '' || $password = '')
        {
            $this->session->set_flashdata('message', 'Username and Password required.');
            $data['apptitle']         = $this->appTitle;
            $data['header_title']        = $this->appTitle;
            $data['header_subtitle']    = "Doña Ramona, Isabela City, Basilan Province";
            $this->load->view('entry_view', $data);
        }
        }

If I try to send an empty form I get a 404 page, which should not be the case because I intend to redirect back to the login page.