i am also facing the same issue. I have header.php in which i have login menu. when i should click that , it display the login form.
Log In .
the strange thing is this plugin works with other themes but its not working with my theme.
i can see in firebug that jquery.simplemodal.js , default.js & jquery.js but with 304 not modified http status.
i donno what is going wrong?
Any help ?