angularJS $http.Post not working: Failed to load resource: Request header field 0 is not allowed by Access-Control-Allow-Headers

I'm using $http to post some data to my data base. Here is the documentation of the database. I use it on my terminal and it works.

Here's the error message I got from Safari's console:

1)Failed to load resource: Request header field 0 is not allowed by Access-Control-Allow-Headers. (seems to be sensed by the database)

2)XMLHttpRequest cannot load https://beta-api.mongohq.com/mongo/MyDId/myDatabse/collections/myCollection/documents. Request header field 0 is not allowed by Access-Control-Allow-Headers.

Here's my code:

factory.sendUrlTag = function(data){
        d = '{"document" : {"url_URL":"53738eef9256a31f4fdf6bf8","tag_Tag":"537375fc9256a31f4fdf6bf3"} }'

        return $http({
        url: 'https://beta-api.mongohq.com/mongo/MyDId/myDatabse/collections/myCollection/documents',
        method: "POST",
        data: d,
        headers: [
             {'Access-Control-Allow-Origin':'*'},
                  {'Access-Control-Allow-Headers':'Origin, X-Requested-With, Content-Type, Accept'},
            {'Content-Type': 'application/json'},
                {'Authorization' : 'api-key MyKey'}
                 ]
    })
    }

    return factory;
};

I didn't have " {'Access-Control-Allow-Origin':'*'}, {'Access-Control-Allow-Headers':'Origin, X-Requested-With, Content-Type, Accept'}," before, but I did some research after I got the error and added these. But it's still not working.

I do $http.get() in my app to the same database and it works.

This thing is driving me nuts.... Please help! Thank you all! :)