How to define received datatype, in backbone.js fetch()?

fetch data from server returns me json data as a string datatype rather than as application/json datatype, as a result the collection does not get refreshed. I have tried giving the jquery.ajax option contentType:"application/json" to the fetch options, but still does not work. how can i make it work? do i send a mimetype from the server? if so, how? i am using json_encode on the data sent. ``` preloader.fetch({ contentType:'application/json' }); ``` preloader is an instance of my collection. edit: my template for a subview was not getting detected as i had kept it out of the masterview's $el element, corrected it, and now i am getting underscore.js error, that str is null in ``` str.replace(/\\/g, '\\\\') //at line 913 ``` is this because the backbone app is not taking it as a json object? Request headers ``` Connection close Content-Type text/html Date Thu, 12 Apr 2012 13:00:58 GMT Server Apache Transfer-Encoding chunked Vary Accept-Encoding ``` Response headers has the line ``` Accept application/json, text/javascript, */*; q=0.01 ``` means it is a json, then what is the problem?