call a c# function from a checkbox onchange

i'm tring to call a function from a onchange attribute to save is value to a tempdata but i run in to a problem, i can't make the data transfer from a javascript

i tried to just put the name or the @functionname but it doesn't work. it seams that the function doesn't fire

@functions{

    public void test2()
    {
        MessageBox.Show("Error Message", "Error Title", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);

    }}