Missing Method in PracticesController

You are seeing this error because the action function.sessionstart is not defined in controller PracticesController

Notice: this error is being rendered by the app/views/errors/missing_action.thtml view file, a user-customizable error page for handling invalid action dispatches.

Fatal: Create Method:

<?php
    class PracticesController extends AppController
    {
        function function.sessionstart()
        {

        }
    }
?>

in file : app/controllers/practices_controller.php

Error: Unable to execute action function.sessionstart in PracticesController