Ajax Post Error (with myjson.com)

var obj = {
    "key": "value",
    "key2": "value2"
};
var data = JSON.stringify(obj);

   $.ajax({
        url: "https://api.myjson.com/bins",
        type: "POST",
        data: data,
        contentType: "application/json; charset=utf-8",
        dataType: "json",
            });
[/code:2tj32oy0]

And in C2 I try
[img="http://iprojects.orgfree.com/myjson/error.jpg"]
With this error
[quote:2tj32oy0]HTTP500 Server Error
{"status":500,"message":"Internal Server Error","more_info":"undefined method `string' for #\u003cPhusionPassenger::Utils::TeeInput:0x007f8039c3fe90\u003e"} 


Please somebody could help?

Thanks