Why is AJAX returning HTTP status code 0?

Question

For some reason, while using AJAX (with my dashcode developed application) the browser just stops uploading and returns status codes of 0. Why does this happen?

Answer 1

In an attempt to win the prize for most dumbest reason for the problem described.

Forgetting to call

xmlhttp.send(); //yes, you need this pivotal line!

Yes, I was still getting status returns of zero from the 'open' call.