jQuery - uncaught reference error!

Ughhhh Annoying… I am using jQuery - and it’s not working for me. Very simply I define a function, and call it. Alas - no - I get the uncaught reference error. Maybe I have done something very stupid - but I cant see it.

THE CODE:

function typer() {	// my code
};
var muse = setTimeout('typer()',500); // uncaught reference error!

SO it’s all about where is the jQuery and how it is being initialised … well ive tried it all …
for starters, im loading it at the very end of my code via a ‘script.js’, just above the … nd ive tried the following

$(document).ready(function () {// my code
});

// U R E

(function($) {// my code
})(jQuery);

// U R E

(function() {// my code
})();

// U R E

Banana’s! they should all work >… IF I just put the code in script tags - then it works …
Any ideas?!