Hopefully, this question isn't too juvenile to ask - but here goes:

I'm trying to learn AJAX, and I'm stuck on a simple content-fetch. Here is my code:

request = getHTTPObject();
function useHttpResponse() {
  if (request.readyState == 4) {
    document.getElementById("p").innerHTML = request.responseText;
  }
}
function update_p() {
  request.open("GET",content.html,true);
  request.onreadystatechange = useHttpResponse;
}

getHTTPObject is correctly defined, and returns a proper XMLHttpObject. As you probably guessed from the excerpt, the element I am trying to update is id'd "p". It calls the script correctly when a button is clicked, no problem there.

The script seems to stop at line 8, at request.open. There's no error, and the script silently ignores anything afterward.

I don't think I've missed anything, but of course, I probably did. Where did I go wrong?

Thanks!