javascript - Backbone.js won't parse modified JSON -

this getting on nerves , don't understand what's causing it. i'm creating prototype backbone.js app using collection fetched static json file mocking database response.

i have view rendering collection data fine, if change single letter in json file fetch method errors!?

by errors mean fetch method error callback fired rather success callback.

the json valid, example i'll change:

{    "hey": "hi" } 

to

{    "hey": "ho" } 

and view no longer renders unless save updated json new filename , update collection url match new filename.

i can't understand why it's doing this? haven't posted javascript code because code fine.

thanks.

edit

parse function:

this.collection.fetch({         success: function(collection, response, options) {           view.render();         }         , error: function(collection, response, options) {           console.log("error");         }       }) 

i don't know how find actual error in objects, response.responsetext json way.