Box Uploading a file: "API upload did not contain a file part" error

Question

I'm having problems trying to upload files via Postman following this documentation: https://developer.box.com/reference#upload-a-file

The error response I'm getting is the following:

{
    "code": "bad_request",
    "help_url": "http://developers.box.com/docs/#errors",
    "status": 400,
    "message": "API upload did not contain a file part",
    "type": "error"
}

The scenario is simple, I want to upload my file located at /Users/myFolder/logo.png to my newly created folder in my Box account

In Postman ,in the tab "Body", with multipart form-data selected, I'm sending the following keys and values:

key: attributes
value:

    {  
        "name": "logo.png",
        "parent": {
            "id": "89972464130"
         }
    }

key: file
value: @/Users/myFolder/logo.png

and in the Headers tab, I'm sending the following keys and values:

key: Content-Type
value: multipart/form-data

key: Authorization
value: Bearer MY_ACCESS_TOKEN

Can you please tell me what I'm doing wrong? I've compared my API call to the one in your Postman Collection and everything seems to be right: https://developer.box.com/docs/box-postman-collection

Thanks in advance!