Unable to receive JSON from JQuery ajax call

Here are a few suggestions I would try:

1) the 'datatype' option you have specified should be 'dataType' (case-sensitive I believe)

2) try using the 'contentType' option as so:

contentType: "application/json; charset=utf-8"

I'm not sure how much that will help as it's used in the request to your post url, not in the response. See this article for more info: http://encosia.com/2008/06/05/3-mistakes-to-avoid-when-using-jquery-with-aspnet-ajax (It's written for asp.net, but may be applicable)

3) Triple check the output of your post url and run the output through a JSON validator just to be absolutely sure it's valid and can be parsed into a JSON object. http://www.jsonlint.com

Hope some of this helps!

Why myResult instead of request?

success: function(request) {
  alert(myResult.length);
}